CONVERTIBLE PROMISSORY NOTE

EXHIBIT 4.2

[Form of]

CONVERTIBLE PROMISSORY NOTE

PHOTOMEDEX, INC.

CONVERTIBLE PROMISSORY NOTE

FOR VALUE RECEIVED, PHOTOMEDEX, INC., a Delaware corporation (the " Company "), promises to pay to the order of Perseus Partners VII, L.P., or its registered assigns (the " Holder "), the Principal Amount, or such lesser amount as shall then equal the outstanding Principal Amount, together with interest thereon at a rate equal to 8.0% per annum, and computed on the basis of a year consisting of 360 days in accordance with the terms set forth in Section 2 of this Convertible Promissory Note (this " Convertible Note ").

This Convertible Note is issued pursuant to the Securities Purchase Agreement, dated as of August 4, 2008 (the " Purchase Agreement "), by and between the Company and Perseus Partners VII, L.P.

The following is a statement of the rights of the Holder and the conditions to which this Convertible Note is subject, and to which the Holder hereof, by the acceptance of this Convertible Note, agrees:

1.   Definitions . Capitalized terms defined in the Purchase Agreement and used herein without definition have the same meaning herein as in the Purchase Agreement. In addition, as used in this Convertible Note, the following capitalized terms have the following meanings:

" Additional Note " shall have the meaning set forth in Section 2(a) of this Convertible Note.

" Conversion Price " means, initially, [                           ] ²   , as adjusted from time to time pursuant to the terms of this Convertible Note.

" Date of Issuance " means the date of issuance of this Convertible Note by the Company under the Purchase Agreement.

" Default Interest Rate " means the lesser of 16% or the maximum rate allowed by applicable Law.

" Event of Default " shall have the meaning set forth in Section 3 of this Convertible Note.

" Maturity Date " means [                           ] ³   (or, if such day is not a Business Day, on the next succeeding Business Day).

" Obligations " means the principal, interest and other amounts payable under this Convertible Note.

2.   Maturity Date; Interest .

(a)   All unpaid principal, together with any accrued but unpaid interest and other amounts payable under this Convertible Note, shall be due and payable on (i) the Maturity Date, or (ii) when such amounts are declared due and payable by the Holder or made automatically due and payable upon or after (A) the occurrence of an Event of Default, (B) the liquidation or dissolution of the Company, or (C) any Change of Control. Interest on this Convertible Note shall be payable (and if not paid when due, shall be compounded) semi-annually in arrears on each [                           ] and [                           ] ⁴   (or, if any such day is not a Business Day, on the next succeeding Business Day) after the Date of Issuance and shall be payable at the option of the Company either (i) in lawful money of the United States of America, or (ii) by the issuance of an additional Note (an " Additional Note ") identical in all respects to this Convertible Note except that it shall have (x) a principal amount equal to such interest payment, (y) an initial Conversion Price equal to the conversion price in effect under this Convertible Note at the date of issuance of such Additional Note and (z) a different date of issuance.

(b)   If the Company elects to pay interest by issuing an Additional Note, it shall give notice to the Holder two Business Days prior to the day such payment is due and deliver such Additional Note to the Holder within three Business Days after such date.

(c)   Interest shall be calculated based on the average principal outstanding under this Convertible Note for such period. The first payment of interest shall be on [                           ] ⁵   (or, if such day is not a Business Day, on the next succeeding Business Day), and shall be calculated from the Date of Issuance to such date.

(d)   Notwithstanding anything to the contrary contained in this Convertible Note, in addition to the rights of the Holder specified in Section 4 of this Convertible Note, for any period during which an Event of Default has occurred and is continuing, the interest rate on this Convertible Note shall increase to the Default Interest Rate and interest on this Convertible Note shall be payable solely in lawful money of the United States of America.

3.   Events of Default . The occurrence of any of the following shall constitute an " Event of Default " under this Convertible Note:

(a)   Failure to Pay this Convertible Note or other Notes .

(b)   Breaches of Representations and Warranties . Any representation or warranty made by the Company in this Convertible Note or in any other Transaction Document shall not have been true and correct in any material respect when made; provided , that if the facts or events making such representation or warranty untrue are capable of correction or cure, then the Company shall have ten Business Days after notice of the breach is delivered to the Company to correct or cure such breach. For purposes of this Section 3(b) only, (i) breaches of the representations and warranties contained in the Purchase Agreement and made as of the First Tranche Closing Date shall be disregarded unless such breaches would, individually or in the aggregate, have given rise to a failure of the condition precedent set forth in Section 6.2(a) of the Purchase Agreement and the Company delivers the certificates required by Section 6.2(e) of the Purchase Agreement, and (ii) breaches of the representations and warranties contained in the Purchase Agreement and made as of the Second Tranche Closing Date shall be disregarded unless such breaches would have, individually or in the aggregate, given rise to a failure of the condition precedent set forth in Section 6.4(a) of the Purchase Agreement and the Company delivers the certificates required by Section 6.4(d) of the Purchase Agreement.

(c)   Breaches of Other Covenants . The Company shall fail to observe or to perform any covenant, obligation, condition or agreement contained in this Convertible Note or any other Transaction Document (other than those specified in Section 3(a) of this Convertible Note) in any material respect; provided , that if such breach is capable of correction or cure, then the Company shall have ten Business Days after notice of the breach is delivered to the Company to correct or cure such breach;

(d)   Cross-Defaults . The Company or any of its Subsidiaries shall default under any other agreement, bond, debenture, note or other evidence of indebtedness for money borrowed (other than a Note), under any guaranty or under any mortgage, or indenture pursuant to which there shall be issued or by which there shall be secured or evidenced any indebtedness for money borrowed by the Company or any of its Subsidiaries, whether such indebtedness now exists or shall hereafter be created, which default shall have resulted in indebtedness of at least $250,000 being due and payable prior to the date on which it would otherwise become due and payable;

(e)   Undischarged Judgment . One or more judgments for the payment of money in an amount in excess of $250,000 in the aggregate shall be rendered against the Company or any of its Subsidiaries (or any combination thereof) and shall remain undischarged for a period of ten consecutive Business Days during which execution shall not be effectively stayed, or any action is legally taken by a judgment creditor to levy upon any such judgment;

(f)   Voluntary Bankruptcy or Insolvency Proceedings . The Company or any of its Subsidiaries shall: (i) apply for or consent to the appointment of a receiver, trustee, liquidator or custodian of itself or of all or a substantial part of its property; (ii) be unable, or admit in writing its inability, to pay its debts generally as they mature; (iii) make a general assignment for the benefit of its or any of its creditors; (iv) be dissolved or liquidated in full or in part; (v) become insolvent (as such term may be defined or interpreted under any applicable statute); (vi) commence a voluntary case or other Proceeding seeking liquidation, reorganization or other relief with respect to itself or its debts under any bankruptcy, insolvency or other similar Law now or hereafter in effect or consent to any such relief or to the appointment of or taking possession of its property by any official in an involuntary case or other Proceeding commenced against it; or (vii) take any action for the purpose of effecting any of the foregoing; or

(g)   Involuntary Bankruptcy or Insolvency Proceedings . Any Proceeding for the appointment of a receiver, trustee, liquidator or custodian of the Company or any of its Subsidiaries or of all or a substantial part of the property thereof, or an involuntary case or other Proceeding seeking liquidation, reorganization or other relief with respect to the Company or any of its Subsidiaries or the debts thereof under any bankruptcy, insolvency or other similar Law now or hereafter in effect shall be commenced and an order for relief entered, or such case or Proceeding shall not be dismissed or discharged within 30 days of commencement.

4.   Rights of Holder upon Default . Upon the occurrence or existence of any Event of Default (other than an Event of Default referred to in Section 3(f) or Section 3(g) of this Convertible Note) and at any time thereafter during the continuance of such Event of Default, holders of a majority of the outstanding principal amount of the Note(s) may declare all outstanding Obligations payable by the Company under this Convertible Note to be immediately due and payable without presentment, demand, protest or any other notice of any kind, all of which are hereby expressly waived, anything contained in this Convertible Note or in any other Transaction Document to the contrary notwithstanding. Upon the occurrence or existence of any Event of Default described in Sections 3(f) or Section 3(g) of this Convertible Note, immediately and without notice, all outstanding Obligations payable by the Company hereunder shall automatically become immediately due and payable, without presentment, demand, protest or any other notice of any kind, all of which are hereby expressly waived, anything contained in this Convertible Note or in any other Transaction Document to the contrary notwithstanding. In addition to the foregoing remedies, upon the occurrence or existence of any Event of Default, the Holder may exercise any other right, power or remedy granted to it pursuant to any Transaction Document or otherwise permitted to it by Law, either by suit in equity or by action at Law, or both.

5.   Covenants . The Company hereby covenants and agrees for the benefit of the Holder as follows:

(a)   Additional Notes . Any Additional Notes issued pursuant to Section 2(a) of this Convertible Note will be, when issued, duly authorized, validly issued, fully paid and nonassessable, free and clear of all Liens other than restrictions on transfer provided for in the Transaction Documents and applicable federal and state securities laws.

(b)   Conversion Shares . All Conversion Shares that may be issued upon the conversion of this Convertible Note and any Additional Notes will be, when issued, duly authorized, validly issued, fully paid and nonassessable, and free from all preemptive rights and Liens other than restrictions on transfer provided for in the Transaction Documents and applicable federal and state securities laws and charges with respect to the issuance thereof. The Company will at all times have authorized and reserved and kept available out of its authorized but unissued shares of Common Stock, solely for the purpose of effecting the conversion of this Convertible Note and any Additional Notes, such number of its shares of Common Stock as shall from time to time be sufficient to effect the conversion of this Convertible Note and all Additional Notes. If at any time the number of authorized but unissued shares of Common Stock shall not be sufficient to effect the conversion of this Convertible Note and all Additional Notes, the Company will take all such corporate actions as may be necessary to increase its authorized but unissued shares of Common Stock to such number of shares as shall be sufficient for such purposes.

(c)   Charges, Taxes and Expenses . Issuance and delivery of the Conversion Shares shall be made without charge to the Holder for any issue or transfer tax, withholding tax (other than related to the income of the Holder), transfer agent fee or other incidental tax or expense in respect of the issuance of such certificates, all of which taxes and expenses shall be paid by the Company; provided, however, that the Company shall not be required to pay any tax which may be payable in respect of any transfer involved in the registration of any certificates for Conversion Shares in a name other than that of the Holder. The Holder shall be responsible for all other tax liability that may arise as a result of holding or transferring this Convertible Note or receiving Conversion Shares.

6.   Prepayment .

(a)   Except as provided in this Section 6 , the Company shall have no right to prepay the principal amount of this Convertible Note prior to the Maturity Date, or any interest accruing under this Convertible Note prior to the scheduled date for payment of such interest.

(b)   If the Market Price as of the fourth anniversary of the First Tranche Closing Date shall be no less than 200% of the conversion price then in effect under the First Tranche Note, then the Company shall have the one-time option to prepay up to one half of the aggregate outstanding principal amount of the Notes, together with accrued but unpaid interest thereon, on the terms and subject to the conditions set forth in Section 5.25 of the Purchase Agreement.

7.   Conversion .

(a)   Optional Conversion . At any time, or from time to time, prior to the Maturity Date, the Holder shall have the option to convert up to the entire amount outstanding under this Convertible Note (including accrued but unpaid interest) into a number of shares of Common Stock equal to the quotient obtained by dividing (i) the amount to be converted by (ii) the Conversion Price then in effect.

(b)   Mandatory Conversion . If on any date occurring at least 31 Trading Days following the Date of Issuance, the Market Price as of such date exceeds 300% of the then-effective Conversion Price, then the entire amount outstanding under this Convertible Note (including accrued but unpaid interest) shall be automatically converted into a number of shares of Common Stock equal to the quotient obtained by dividing (i) the amount outstanding under this Convertible Note (including accrued but unpaid interest) by (ii) the Conversion Price then in effect. The Company shall notify the Holder promptly (and in any event not later than three Business Days) following any mandatory conversion of this Convertible Note pursuant to this Section 7(b) .

(c)   Mechanics and Effect of Conversion . No fractional shares of Common Stock shall be issued upon conversion of this Convertible Note. Upon the conversion of all of the principal and accrued interest outstanding under this Convertible Note, in lieu of the Company issuing any fractional shares to the Holder, the Company shall pay to the Holder the amount of outstanding principal and accrued interest that is not so converted. Upon any partial conversion of this Convertible Note, the Company shall issue to the Holder (i) the shares of Common Stock into which the applicable portion of the principal and accrued interest under this Convertible Note is converted and (ii) a new Note identical in all respects to this Convertible Note except that it shall have a principal amount equal to the difference between (1) the outstanding principal amount of this Convertible Note immediately prior to such conversion minus (2) the portion of such outstanding principal amount converted into shares of Common Stock. Upon any conversion of this Convertible Note pursuant to this Section 7 , the Holder shall surrender this Convertible Note, duly endorsed, at the principal