COMMON STOCK PURCHASE WARRANT BIOVEST INTERNATIONAL, INC

EXHIBIT 10.5

NEITHER THIS SECURITY NOR THE SECURITIES FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH APPLICABLE STATE SECURITIES LAWS AS EVIDENCED BY A LEGAL OPINION OF COUNSEL TO THE TRANSFEROR TO SUCH EFFECT, THE SUBSTANCE OF WHICH SHALL BE REASONABLY ACCEPTABLE TO THE COMPANY. THIS SECURITY AND THE SECURITIES ISSUABLE UPON EXERCISE OF THIS SECURITY MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER LOAN SECURED BY SUCH SECURITIES.

COMMON STOCK PURCHASE WARRANT

BIOVEST INTERNATIONAL, INC.

THIS COMMON STOCK PURCHASE WARRANT (the “ Warrant ”) certifies that, for value received,                                          (the “ Holder ”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date hereof (the “ Initial Exercise Date ”) and on or prior to the close of business on the 5 year anniversary of the Initial Exercise Date (the “ Termination Date ”) but not thereafter, to subscribe for and purchase from Biovest International, Inc., a Delaware corporation (the “ Company ”), up to                      shares (the “ Warrant Shares ”) of Common Stock. The purchase price of one share of Common Stock under this Warrant shall be equal to the Exercise Price, as defined in Section 2(b).

Section 1 . Definitions . Capitalized terms used and not otherwise defined herein shall have the meanings set forth in that certain Securities Purchase Agreement (the “ Purchase Agreement ”), dated September 19, 2008, among the Company and the purchasers signatory thereto.

Section 2 . Exercise .

a) Exercise of Warrant . Exercise of the purchase rights represented by this Warrant may be made, in whole or in part, at any time or times on or after the Initial Exercise Date and on or before the Termination Date by delivery to the Company (or such other office or agency of the Company as it may designate by notice in writing to the registered Holder at the address of the Holder appearing on the books of the Company) of a duly executed facsimile copy of the Notice of Exercise Form annexed

1

hereto; and, within three (3) Trading Days of the date said Notice of Exercise is delivered to the Company, the Company shall have received payment of the aggregate Exercise Price of the shares thereby purchased by wire transfer or cashier’s check drawn on a United States bank. Notwithstanding anything herein to the contrary, the Holder shall not be required to physically surrender this Warrant to the Company until the Holder has purchased all of the Warrant Shares available hereunder and the Warrant has been exercised in full, in which case, the Holder shall surrender this Warrant to the Company for cancellation within three (3) Trading Days of the date the final Notice of Exercise is delivered to the Company. Partial exercises of this Warrant resulting in purchases of a portion of the total number of Warrant Shares available hereunder shall have the effect of lowering the outstanding number of Warrant Shares purchasable hereunder in an amount equal to the applicable number of Warrant Shares purchased. The Holder and the Company shall maintain records showing the number of Warrant Shares purchased and the date of such purchases. The Company shall deliver any objection to any Notice of Exercise Form within one (1) Business Day of receipt of such notice. The Holder and any assignee, by acceptance of this Warrant, acknowledge and agree that, by reason of the provisions of this paragraph, following the purchase of a portion of the Warrant Shares hereunder, the number of Warrant Shares available for purchase hereunder at any given time may be less than the amount stated on the face hereof.

b) Exercise Price . The exercise price per share of the Common Stock under this Warrant shall be $0.40 , subject to adjustment hereunder (the “ Exercise Price ”).

c) Cashless Exercise . If at any time after the completion of the then-applicable holding period required by Rule 144, or any successor provision then in effect, this Warrant may be exercised at such time by means of a “cashless exercise” in which the Holder shall be entitled to receive a certificate for the number of Warrant Shares equal to the quotient obtained by dividing [(A-B) (X)] by (A), where:

2

d) Exercise Limitations .

Holder’s Restrictions. Notwithstanding anything herein to the contrary, in no event shall the Holder be entitled to exercise any portion of this Warrant in excess of that portion of this Warrant upon exercise of which the sum of (1) the number of shares of Common Stock beneficially owned by the Holder and its Affiliates (other than shares of Common Stock which may be deemed beneficially owned through the ownership of the unexercised portion of this Warrant or the unexercised or unconverted portion of any other security of the Holder subject to a limitation on conversion analogous to the limitations contained herein) and (2) the number of shares of Common Stock issuable upon the exercise of the portion of this Warrant with respect to which the determination of this proviso is being made, would result in beneficial ownership by the Holder and its Affiliates of any amount greater than 9.99% of the then outstanding shares of Common Stock (whether or not, at the time of such exercise, the Holder and its Affiliates beneficially own more than 9.99% of the then outstanding shares of Common Stock). As used herein, the term “Affiliate” means any person or entity that, directly or indirectly through one or more intermediaries, controls or is controlled by or is under common control with a person or entity, as such terms are used in and construed under Rule 144 under the Securities Act of 1933, as amended. For purposes of the second preceding sentence, beneficial ownership shall be determined in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended, and Regulations 13D-G thereunder, except as otherwise provided in clause (1) of such sentence. For any reason at any time, upon written or oral request of the Holder, the Company shall within one (1) business day confirm orally and in writing to the Holder the number of shares of Common Stock outstanding as of any given date. The limitations set forth herein (x) shall automatically become null and void following notice to the Company upon the occurrence and during the continuance of an Event of Default (as defined in the Security Agreement) and (y) may be waived by the Holder upon provision of no less than sixty-one (61) days prior written notice to the Company; provided, however, that, such written notice of waiver shall only be effective if delivered at a time when no indebtedness (including, without limitation, principal, interest, fees and charges) of the Company of which the Holder or any of its Affiliates was, at any time, the owner, directly or indirectly is outstanding. The limitations contained in this paragraph shall apply to a successor holder of this Warrant.

Holder’s Restrictions. Notwithstanding anything herein to the contrary, in no event shall the Holder be entitled to exercise any portion of this Warrant in excess of that portion of this Warrant upon exercise of which the sum of (1) the number of shares of Common Stock beneficially owned by the Holder and its Affiliates (other than shares of Common Stock which may be deemed beneficially owned through the ownership of the unexercised portion of this Warrant or the unexercised or unconverted portion of any other security of the Holder subject to a limitation on conversion analogous to the limitations contained herein) and (2) the number of shares of Common Stock issuable upon conversion of this Debenture held by the Holder. The Holder, within ten (10) days of the issuance of this Debenture and thereafter upon not less than 61 days’ prior notice to the Company, may increase or decrease the Beneficial Ownership Limitation provisions of this Section 4(c), provided that the Beneficial Ownership Limitation in no event exceeds 9.99% of the number of shares of the Common Stock outstanding immediately after giving effect to the issuance of shares of Common Stock upon conversion of this Debenture held by the Holder and the Beneficial Ownership Limitation provisions of this Section 4(c) shall continue to apply. Any such increase or decrease will not be effective until the 61st day after such notice is delivered to the Company. The Beneficial Ownership Limitation provisions of this paragraph shall be construed and implemented in a manner otherwise than in strict conformity with the terms of this Section 4(c) to correct this paragraph (or any portion hereof) which may be defective or inconsistent with the intended Beneficial Ownership Limitation contained herein or to make changes or supplements necessary or desirable to properly give effect to such limitation. The limitations contained in this paragraph shall apply to a successor holder of this Debenture.the exercise of the portion of this Warrant with respect to which the determination of this proviso is being made, would result in beneficial ownership by the Holder and its Affiliates of any amount greater than 4.99% of the then outstanding shares of Common Stock (whether or not, at the time of such exercise, the Holder and its Affiliates beneficially own more than 4.99% of the then outstanding shares of Common Stock). As used herein, the term “Affiliate” means any person or entity that, directly or indirectly through one or more intermediaries, controls or is controlled by or is under common control with a person or entity, as such terms are used in and construed under Rule 144 under the Securities Act of 1933, as amended. For purposes of the second preceding sentence, beneficial ownership shall be determined in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended, and Regulations 13D-G thereunder, except as otherwise provided in clause (1) of such sentence. For any reason at any time, upon written or oral request of the Holder, the Company shall within one (1) business day confirm orally and in writing to the Holder the number of shares of Common Stock outstanding as of any given date. The limitations set forth herein (x) shall automatically become null and void following notice to the Company upon the occurrence and during the continuance of an Event of Default (as defined in the Security Agreement) and (y) may be waived by the Holder upon provision of no less than sixty-one (61) days prior written notice to the Company; provided, however, that, such written notice of waiver shall only be effective if delivered at a time when no indebtedness (including, without limitation, principal, interest, fees and charges) of the Company of which the Holder or any of its Affiliates was, at any time, the owner, directly or indirectly is outstanding. The limitations contained in this paragraph shall apply to a successor holder of this Warrant.

3

e) Mechanics of Exercise .

i. Delivery of Certificates Upon Exercise . Certificates for Warrant Shares shall be transmitted by the Transfer Agent to the Holder by crediting the account of the Holder’s prime broker with the Depository Trust Company through the Deposit Withdrawal Agent Commission (“ DWAC ”) system if the Company is then a participant in such system and the Warrant Shares are eligible for resale without volume or manner-of-sale limitations pursuant to Rule 144, and otherwise by physical delivery to the address specified by the Holder in the Notice of Exercise within 3 Trading Days from the delivery to the Company of the Notice of Exercise Form, surrender of this Warrant (if required) and payment of the aggregate Exercise Price as set forth above (the “ Warrant Share Delivery Date ”). This Warrant shall be deemed to have been exercised on the date the Exercise Price is received by the Company. The Warrant Shares shall be deemed to have been issued, and Holder or any other person so designated to be named therein shall be deemed to have become a holder of record of such shares for all purposes, as of the date the Warrant has been exercised by payment to the Company of the Exercise Price (or by cashless exercise, if permitted) and all taxes required to be paid by the Holder, if any, pursuant to Section 2(e)(v) prior to the issuance of such shares, have been paid.

ii. Delivery of New Warrants Upon Exercise . If this Warrant shall have been exercised in part, the Company shall, at the request of a Holder and upon surrender of this Warrant certificate, at the time of delivery of the certificate or certificates representing Warrant Shares, deliver to Holder a new Warrant evidencing the rights of Holder to purchase the unpurchased Warrant Shares called for by this Warrant, which new Warrant shall in all other respects be identical with this Warrant.

iii. Rescission Rights . If the Company fails to cause the Transfer Agent to transmit to the Holder a certificate or the certificates representing the Warrant Shares pursuant to Section 2(e)(i) by the Warrant Share Delivery Date, then, the Holder will have the right to rescind such exercise.

4

iv. No Fractional Shares or Scrip . No fractional shares or scrip representing fractional shares shall be issued upon the exercise of this Warrant. As to any fraction of a share which Holder would otherwise be entitled to purchase upon such exercise, the Company shall, at its election, either pay a cash adjustment in respect of such final fraction in an amount equal to such fraction multiplied by the Exercise