FORM OF SUBSCRIPTION AND REGISTRATION RIGHTS AGREEMENT

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EXHIBIT 99.1

FORM OF

SUBSCRIPTION AND REGISTRATION RIGHTS AGREEMENT

This Subscription and Registration Rights Agreement (this "Agreement"),

made as of the date set forth below by and between Carrizo Oil & Gas, Inc. (the

"Company") and the undersigned (the "Subscriber" and, together with the other

subscribers for Shares (as defined below), the "Subscribers") is intended to set

forth certain representations, covenants and agreements between the Company and

the Subscriber with respect to the offering (the "Offering") for sale by the

Company of up to 1,200,000 shares (the "Shares") of common stock, par value

$0.01 per share (the "Common Stock"), as described in the Company's Confidential

Private Placement Memorandum dated June 7, 2005, as supplemented (the

"Memorandum"), a copy of which has been delivered to the Subscriber. The Shares

are being offered by the Company through Hibernia Southcoast Capital, Inc., as

the Company's managing placement agent (the "Placement Agent").

1. Subscription. Subject to the terms and conditions hereof, the

Subscriber hereby irrevocably subscribes for and agrees to purchase from the

Company the number of Shares set forth under the Subscriber's name on the

signature page hereto at a purchase price of $15.25 per share (the "Offering

Price"), and the Company agrees to sell such Shares to the Subscriber at the

Offering Price, subject to the Company's right to sell to the Subscriber such

lesser number of Shares as the Company may, in its sole discretion, deem

necessary or desirable.

2. Delivery of Subscription Amount; Acceptance of Subscription; Delivery

of Shares. The Subscriber understands, acknowledges and agrees that this

subscription is made subject to the following terms and conditions:

(a) The Subscriber understands that separate subscription agreements

may be executed with other Subscribers for any remaining Shares to be sold

in the Offering;

(b) The Subscriber must be an institution that is (i) currently a

security holder of the Company and (ii) an "accredited investor" as

defined in Rule 501(a)(1), (2), (3), (7) or (8) of Regulation D under the

Securities Act of 1933, as amended (the "Securities Act");

(c) Contemporaneously with the completion, execution and delivery of

this Agreement, the Subscriber shall complete, execute and deliver, in

accordance with the instructions set forth on Exhibit A attached hereto,

the Certificate of Accredited Investor Status attached hereto as Exhibit

B. Contemporaneously with or prior to Closing (as defined below), the

Subscriber shall wire to the Company to hold in a separate,

non-interest-bearing account, immediately available United States funds in

the amount equal to the Offering Price multiplied by the number of Shares

for which the Subscriber has subscribed (the "Subscription Amount") in

accordance with the instructions set forth on Exhibit A attached hereto;

(d) The Company is offering for sale up to 1,200,000 Shares at the

Offering Price, for an aggregate price of the Offering of up to $15.25;

(e) The Subscriber shall have the right to cancel the Subscriber's

subscription and

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withdraw the proceeds representing the Subscription Amount at any time

during the Offering if the Closing shall not have occurred prior to June

15, 2005;

(f) The subscription for Shares shall be deemed to be accepted only

when this Agreement has been signed by an authorized executive officer of

the Company, on behalf of the Company. The deposit of the Subscription

Amount for clearance will not be deemed an acceptance of this Agreement;

(g) The Subscriber understands and acknowledges that (i) the Company

has the unconditional right, exercisable in its sole and absolute

discretion, to accept or reject the subscriber's subscription for Shares,

in whole or in part, (ii) subscriptions need not be accepted by the

Company in the order received by the Company, (iii) all subscriptions are

subject to prior sale, withdrawal, modification or cancellation of the

Offering by the Company, (iv) no subscription shall be valid unless and

until accepted by the Company, (v) the Subscriber's subscription for

Shares shall be deemed to be accepted by the Company only when this

Agreement is signed by an authorized executive officer of the Company, on

behalf of the Company, (vi) the Company shall have the right to allocate

Shares among the Subscribers in any manner it may desire; provided,

however, that no Subscriber shall be obligated to purchase more than the

number of Shares set forth under its name on the signature page hereto

without its prior written consent, and (vii) notwithstanding anything in

this Agreement to the contrary, the Company shall have no obligation to

issue Shares to any person to whom the issuance of Shares would constitute

a violation of the Securities Act or any state securities laws;

(h) The payment of the Subscription Amount (or, in the case of

rejection of a portion of the Subscriber's subscription, the part of the

payment relating to such rejected portion) will be returned promptly,

without interest, if the Subscriber's subscription is rejected in whole or

in part or if the Offering is withdrawn or canceled;

(i) Certificates representing the Shares purchased will be issued in

the name of each Subscriber as soon as reasonably practicable on or after

Closing as set forth under Section 3 hereof;

(j) The Offering is being conducted on a "best efforts" basis, and

the Company is not required to accept any minimum aggregate amount of

subscriptions before conducting a Closing; and

(k) The representations and warranties of the Company and the

Subscriber set forth herein shall be true and correct as of the date that

the Company accepts this subscription.

3. Terms of Subscription.

(a) The subscription period will begin as of June 7, 2005 and will

terminate at 11:59 p.m. Eastern Time on June 20, 2005, unless extended by

the Company, on one or more occasions for up to an additional 60 days (the

"Termination Date"), which extension may be effected without notice to the

Subscribers. The purchase and sale of the Shares (the "Closing") shall

occur as soon as practicable after the execution of this Agreement by the

Company and each of the Subscribers in the Offering at a time (the

"Closing Date") and location agreed upon by the Company and the Placement

Agent. As soon as reasonably

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practicable on or after the Closing Date, the Company will deliver or

cause to be delivered, one or more physical certificates representing the

Shares purchased by each Subscriber.

(b) In consideration of the Placement Agent's services rendered to

the Company as its managing placement agent in connection with the

Offering, the Company will pay the Placement Agent a fee equal to five

percent (5%) of the gross proceeds received by the Company in connection

with the sale of Shares in the Offering. The Subscriber understands that

the Company will also pay all of the Placement Agent's expenses in

connection with the Offering as previously agreed upon by the Company and

the Placement Agent.

4. Registration Rights.

(a) Within 30 days after the Closing Date, or within such 30-day

period as extended by such additional number of days as are attributable

to any delay caused by any act or failure to act by any of the Subscribers

or their counsel, the Company shall use its commercially reasonable

efforts to prepare and file with the Securities and Exchange Commission

(the "SEC"), a registration statement (the "Registration Statement") and

such other documents as may be necessary or appropriate in the opinion of

counsel for the Company and shall use its commercially reasonable efforts

to have such Registration Statement declared effective as soon as

practicable after the filing date in order to comply with the provisions

of the Securities Act, so as to permit the registered resale or other

disposition of the Shares for a period of two (2) years following the

Closing Date by each and every holder of Shares sold in the Offering

except for those holders who designate on the signature page hereto that

they do not wish to have their Shares included in the Registration

Statement. The Shares that are registered for resale under such

Registration Statement are referred to herein as the "Offering Shares,"

and the Subscribers who are eligible to sell their Shares under such

Registration Statement, together with their respective affiliates, are

hereafter referred to as "Offering Holders." The Company will include in

such Registration Statement (i) the information required under the

Securities Act to be so included concerning the Offering Holders, as

provided by the Offering Holders on the signature pages to this Agreement

and the other Subscription and Registration Rights Agreements entered into

in connection with the Offering, including the information specified by

Items 507 and 508 of Regulation S-K under the Securities Act and any

changes in such information that may be provided by the Offering Holders

in writing to the Company from time to time, and (ii) a section entitled

"Plan of Distribution," substantially in the form of Exhibit C attached

hereto (with such changes thereto as may be required by the SEC or

otherwise as may be required to comply with applicable law or regulation),

that describes the various procedures that may be used by the Offering

Holders in the sale of Offering Shares.

(b) In the event that the Company does not file a Registration

Statement to register the Offering Shares with the SEC within thirty (30)

days following the closing of the Offering, or within such 30-day period

as extended by such additional number of days as are attributable to any

delay caused by any act or failure to act by any of the Subscribers or

their counsel, the Company will be required to pay liquidated damages to

each Offering Holder equal to one percent (1%) of such Offering Holder's

purchase price ($15.25 per Share) for the Offering Shares, and an

additional one percent (1%) of such Offering Holding's purchase price

($15.25 per Share) for the Offering Shares for each additional 30-day

period during

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which such Registration Statement is not filed.

(c) Notwithstanding the foregoing provisions of this Section 4, the

Company may voluntarily suspend the effectiveness of any such Registration

Statement for a limited time or may otherwise require the discontinuance

of offers and transfers under the Registration Statement, which in no

event shall be longer than 30 days in any three-month period and no longer

than 60 days in any twelve month period, if (i) the Company has been

advised by counsel or underwriters to the Company that the offering of any

Offering Shares pursuant to the Registration Statement would materially

adversely affect, or would be improper in view of (or improper without

disclosure in a prospectus), a proposed financing, a reorganization,

recapitalization, merger, consolidation, or other transaction involving

the Company or (ii) any event occurs that would cause any such

Registration Statement to contain a material misstatement or omission or

not to be effective and usable during the period that such Registration

Statement is required to be effective and usable (in either case, a

"Suspension"). The Company shall be deemed to be in breach of this

Agreement if it shall require any Suspension in excess of the time periods

set forth above. The Company shall notify all Offering Holders of any

Suspension and, upon receipt of such notice, each such Offering Holder

will discontinue any offers or transfers sales of Offering Shares pursuant

to the Registration Statement until such Offering Holder has received

copies of a supplemented or amended prospectus or until such Offering

Holder is advised in writing by the Company that the then current

prospectus may be used. In the event of a Suspension as described in

clause (ii) above, the Company shall promptly notify the Offering Holders

to that effect and, if requested, the Offering Holders shall immediately

cease making offers or transfers of Offering Shares and return all

prospectuses to the Company. The Company shall promptly file a supplement

or an amendment to the Registration Statement or a document incorporated

by reference into the Registration Statement to correct such misstatement

or omission and use its commercially reasonable efforts to cause any such

amendment to be declared effective as soon as practicable thereafter. The

Company shall promptly provide the Offering Holders with revised

prospectuses and, following receipt of the revised prospectuses, the

Offering Holders shall be free to resume making offers of the Offering

Shares. Notwithstanding any provision contained herein to the contrary,

the Company's obligation to include, or continue to include, Offering

Shares in the Registration Statement under this Section 4 shall terminate

to the extent such Offering Shares are eligible for resale under Rule

144(k) promulgated under the Securities Act.

(d) If and whenever the Company is required by the provisions of

this Agreement to use its commercially reasonable efforts to effect the

registration of the Offering Shares under the Securities Act for the

account of an Offering Holder, the Company will, in addition, as promptly

as practicable:

(i) use commercially reasonable efforts to prepare and file

with the SEC, promptly upon the reasonable request of any

Subscriber, such amendments and supplements to such Registration

Statement and the prospectus used in connection therewith as may be

necessary to keep such Registration Statement effective and to

comply with the requirements of the Securities Act and the rules and

regulations promulgated by the SEC thereunder relating to the sale

or other disposition of the securities covered by such Registration

Statement; and

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(ii) furnish to each Offering Holder such numbers of copies of

a prospectus, complying with the requirements of the Securities Act,

and such other documents as such Offering Holder may reasonably

request in order to facilitate the public sale or other disposition

of the Offering Shares owned by such Offering Holder, but such

Offering Holder shall not be entitled to use any selling materials

other than a prospectus and such other materials as may be approved

by the Company, which approval will not be unreasonably withheld.

(e) At any time when a prospectus relating to the Offering is

required to be delivered under the Securities Act:

(i) the Company will notify the Offering Holder, upon the

awareness of an executive officer of the Company, if the prospectus

included in such Registration Statement, as then in effect, includes

an untrue statement of material fact or omits to state a material

fact required to be stated therein or necessary to make the

statements therein not misleading in light of the circumstances then

existing. Upon receipt of such notice, the Offering Holders will

make no further sales or other dispositions, or offers therefor, of

Offering Shares under the Registration Statement until they receive

from the Company copies of a new, amended or supplemented prospectus

complying with the Securities Act or until the Company has filed an

appropriate report with the SEC pursuant to the Securities Exchange

Act of 1934, as amended (the "Exchange Act"), which filing shall be

made as promptly as reasonably practicable; and

(ii) the Subscriber will notify the Company of the happening

of any event relating to the Subscriber as a result of which the

prospectus included in such Registration Statement, as then in

effect, includes an untrue statement of material fact or omits to

state a material fact required to be stated therein or necessary to

make the statements therein not misleading in light of the

circumstances then existing, and the Subscriber shall promptly make

available to the Company information necessary to enable the Company

to prepare a new, amended or supplemented prospectus or to file an

appropriate report with the SEC pursuant to the Exchange Act which

preparation or filing shall be made as soon as reasonably

practicable.

(f) The Subscriber agrees not to take any action with respect to any

distribution deemed to be made pursuant to such Registration Statement

that constitutes a violation of Regulation M under the Exchange Act or any

other applicable rule, regulation or law.

(g) The Subscriber acknowledges and agrees that in the event of

sales under a Registration Statement pursuant to this Agreement, the

Offering Shares sold pursuant to such Registration Statement are not

transferable on the books of the Company unless the share certificate

submitted to the transfer agent evidencing such Offering Shares is

accompanied by a certificate reasonably satisfactory to the Company to the

effect that (A) the Offering Shares have been sold in accordance with such

Registration Statement and (B) the requirement of delivering a current

prospectus has been satisfied.

(h) The Subscriber acknowledges and agrees that it will keep

confidential all nonpublic information it receives in connection with this

Agreement and that such information be neither used for the Subscriber's

personal benefit (other than in connection

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with the subscription) nor disclosed to any third party for any reason.

This shall include, without limitation, the receipt of any notice of any

suspension of the offering and sale of the Offering Shares pursuant to the

provisions of Section 4(c) hereof in the event the Company notifies the

Subscriber that such notice constitutes material nonpublic information;

provided, however, that the number of days during which the Subscriber

must keep confidential such information or any other information it

receives from the Company in connection with this Agreement that the

Company designates as material nonpublic information shall be counted

toward the satisfaction of the 30- and 60-day periods of voluntary

suspension set forth in Section 4(c) (with any such days prior to the date

of effectiveness of the Registration Statement being counted toward the

satisfaction of the voluntary suspension periods during the first 30 days

or 12 months, as the case may be, following effectiveness). This Section

4(h) shall not apply to any information that is or becomes publicly

available through no fault of the Subscriber or that the Subscriber is

legally required to disclose by a governmental entity or other third

party; provided, however, that if the Subscriber is requested or ordered

to disclose any such information pursuant to any court or other government

order or any other applicable legal procedure, it shall cooperate with the

Company and provide the Company with prompt notice of any such request or

order, unless the Subscriber is legally prohibited from providing such

notice, in time sufficient to enable the Company to seek an appropriate

protective order. The Company acknowledges and agrees that upon and at the

time of the filing of the Form 8-K described in Section 5(v), the

Subscriber shall not be in possession of any material nonpublic

information related to this Agreement.

(i) Except as provided below in this Section 4, the expenses

incurred by the Company in connection with action taken by the Company to

comply with this Section 4, including, without limitation, all

registration and filing fees, printing and delivery expenses, accounting

fees, fees and disbursements of counsel to the Company, consultant and

expert fees, premiums for liability insurance, if the Company chooses to

obtain such insurance, obtained in connection with a registration

statement filed to effect such compliance and all expenses, including

counsel fees, of complying with any state securities laws, shall be paid

by the Company; provided, however, that each Offering Holder shall bear

its own selling expenses, brokerage fees, commissions and similar payments

and transfer taxes attributable to the Offering Shares being sold by such

Offering Holder and shall bear fees and expenses of its own counsel and

other advisors, if any.

(j) In the event of any registration of Shares pursuant to this

Section 4, the Company will, to the maximum extent permitted by law,

indemnify and hold harmless each Offering Holder and each person, if any,

who controls an Offering Holder within the meaning of Section 15 of the

Securities Act (collectively, the "Indemnified Parties") against any

losses, claims, damages, or liabilities, joint or several, to which any of

such Indemnified Parties may become subject under the Securities Act or

otherwise, insofar as such losses, claims, damages or liabilities (or

actions in respect thereof) are caused by any untrue statement of any

material fact contained in the registration statement, any prospectus

contained therein, or any amendment or supplement thereof, or arising out

of or based upon the omission to state therein a material fact required to

be stated therein or necessary to make the statements therein not

misleading and will reimburse such Indemnified Parties for any reasonable

legal or other expenses they incur in connection with investigating or

defending against any such loss, claim, damage, liability or action;

provided, however, that the Company will not be

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liable to the extent that any such loss, claim, damage, expense or

liability arises out of, or is based upon, an untrue statement or alleged

untrue statement or omission or alleged omission so made in conformance

with information that has been furnished in writing by such indemnified

party in accordance with Section 5(l) hereof; and, provided further, that

the Company shall not be required to provide such indemnification if such

loss, claim, damage or liability (or action in respect thereof) arises out

of or is based upon an untrue statement or alleged untrue statement or

omission or alleged omission made in any final prospectus and if, in

respect to such statement, alleged statement, omission or alleged

omission, a more current prospectus corrected such statement or omission

and was delivered to the Offering Holder and a copy of such more current

prospectus had not been sent or given at or prior to the confirmation of

the sale with respect to which such loss, claim, damage, expense or

liability relates. The indemnification provided for herein shall be

applicable, regardless of whether any such losses, claims, damages, or

liabilities result solely or in part from the active, passive or

concurrent negligence or strict liability of the indemnitee.

(k) In the event of any registration of Shares pursuant to this

Section 4, the Subscriber will, to the maximum extent permitted by law,

indemnify and hold harmless the Company, each of its directors, each of

its officers who has signed the Registration Statement, and each person,

if any, who controls the Company, within the meaning of the Securities Act

(collectively, the "Indemnified Persons"), against any loss, claim, damage

or liability of which the Company or any such Indemnified Person may be or

become subject under the Securities Act or otherwise, insofar as such

loss, claim, damage or liability (or action in respect thereof) is caused

by any untrue statement of any material fact contained in the Registration

Statement, such prospectus, or amendment or supplement thereof, or arises

out of or is based upon the omission to state therein a material fact

required to be stated therein or necessary to make the statements therein

not misleading, or arises out of or is based on any failure by the

Subscriber to comply with the covenants or agreements contained in this

Agreement with respect to Offering Shares, in each case to the extent, but

only to the extent, that such untrue statement or alleged untrue statement

or omission or alleged omission relates to the information that has been

furnished in writing by such Subscriber in accordance with Section 5(l)

hereof and will reimburse the Company and each such officer, director and

controlling person for any reasonable legal or other expenses they incur

in connection with investigating or defending against any such loss,

claim, damage, liability or action. The indemnification provided for

herein shall be applicable, regardless of whether any such losses, claims,

damages, or liabilities result solely or in part from the active, passive

or concurrent negligence or strict liability of the indemnitee.

(l) Promptly after receipt by an indemnified party as described in

Section 4(j) or 4(k) hereof of notice of the commencement of any action,

such indemnified party will, if a claim thereof is to be made against the

indemnifying party pursuant thereto, notify the indemnifying party of the

commencement thereof, but the omission to notify the indemnifying party

will not relieve it from any liability which it may have to any

indemnified party except to any extent to which the indemnifying party is

actually prejudiced thereby. In case such action is brought against any

indemnified party, and it notifies the indemnifying party of the

commencement thereof, the indemnifying party will be entitled to

participate in, and, to the extent that it may wish, jointly with any

other indemnifying party, similarly notified, to assume the defense

thereof, with counsel reasonably satisfactory to such

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indemnified party. An indemnified party shall not be liable for any

settlement of an action or claim effected without its written consent

(which shall not be unreasonably withheld or delayed). An indemnifying

party who is entitled to, or elects to, assume the defense of a claim

shall have the right to employ its counsel in such claim or action, unless

in the reasonable judgment of any indemnified party a conflict of interest

may exist between such indemnified party and any other of such indemnified

parties with respect to such claim that makes the representation by such

counsel inappropriate, in which case the indemnifying party shall select

separate counsel for such indemnified party reasonably acceptable to such

indemnified party; provided, however, that the indemnifying party will not

be obligated to pay the fees and expenses of more than one counsel (other

than local counsel as reasonably required) for all parties indemnified by

such indemnifying party with respect to such claim.

(m) If the indemnification provided for in Section 4(j) or Section

4(k) hereof is unavailable to an indemnified party thereunder in respect

to any losses, claims, damages, liabilities or expenses referred to

therein, then each indemnifying party, in lieu of indemnifying such

indemnified party, shall contribute to the amount paid or payable by such

indemnified party as a result of such losses, claims, damages, liabilities

or expenses in such proportion as is appropriate to reflect the relative

fault of the Company, on the one hand, and all shareholders offering

securities via the Registration Statement (the "Selling Shareholders"), on

the other hand, in connection with the statements or omissions that

resulted in such losses, claims, damages, liabilities or expenses, as well

as any other relevant equitable considerations. The relative fault of the

Company on the one hand and the Selling Shareholders on the other shall be

determined by reference to, among other things, whether the untrue or

alleged untrue statement of material facts or the omission or alleged

omission to state a material fact relates to information supplied by the

Company or by the Selling Shareholders and the parties' relative intent,

knowledge, access to information and opportunity to correct such statement

or omission. The Company and the Selling Shareholders agree that it would

not be just and equitable if contribution pursuant to this Section 4(m)

were based solely on the number of entities from whom contribution was

requested or by any other method of allocation that does not take account

of the equitable considerations referred to above in this Section 4(m).

The amount paid or payable by an indemnified party as a result of the

losses, claims, damages, expenses and liabilities referred to above in

this Section 4(m) shall be deemed to include any legal or other expenses

reasonably incurred by such indemnified party in connection with

investigating or defending any such action or claim, subject to the

provisions of Section 4(l) hereof. No person guilty of fraudulent

misrepresentation (within the meaning of Section 11(f) of the Securities

Act) shall be entitled to contribution from any person who was not guilty

of such fraudulent misrepresentation.

(n) Notwithsta