BIOVEST INTERNATIONAL, INC. COMMON STOCK PURCHASE WARRANT

EXHIBIT 10.3

WARRANT

Dated as of October 15, 2008

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES LAW OF ANY STATE AND MAY NOT BE SOLD, TRANSFERRED OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES LAWS OR PURSUANT TO AN APPLICABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF SUCH ACT AND SUCH LAWS.

BIOVEST INTERNATIONAL, INC.

COMMON STOCK PURCHASE WARRANT

Void after October 14, 2013

BIOVEST INTERNATIONAL, INC. (the “Company”), a Delaware corporation, hereby certifies that for value received, specifically but without limitation in consideration of forbearance in exercising his rights and/or instituting efforts at collection pursuant to an existing Promissory Note dated September 10, 2007 pending negotiations regarding the restructure of that Promissory Note, Philip E. Rosensweig (including any transferee, the “Holder”), are entitled to purchase, subject to the terms and conditions hereinafter set forth, at any time or from time to time beginning on October 15, 2008 (the “Exercise Date”) and ending prior to 5:00 P.M., New York City time, on October 14, 2013 (the “Expiration Date”) up to 375,000 shares of Common Stock at an exercise price per share of $0.40 per share subject to adjustment as provided herein (the “Purchase Price”).

This Warrant is issued in connection with a forbearance arrangement between the Holder and the Company.

1. Definitions . For the purposes of this Warrant, the following terms shall have the meanings indicated:

“ Business Day ” shall mean any day other than a Saturday, Sunday or other day on which commercial banks in the City of New York are authorized or required by law or executive order to close.

“ Closing Price ” shall mean, with respect to each share of Common Stock for any day, (a) the last reported sale price regular way or, in case no such sale takes place on such day, the average of the closing bid and asked prices regular way, in either case as reported on the principal national securities exchange on which the Common Stock is listed or admitted for trading or (b) if the Common Stock is not listed or admitted for trading on any national securities exchange, the last reported sale price or, in case no such sale takes place on such day, the average of the highest reported bid and the lowest reported asked quotation for the Common Stock, in either case as reported on the NASDAQ or a similar service if NASDAQ is no longer reporting such information.

“ Common Stock ” means the common stock, no par value, of the Company, and any class of stock resulting from successive changes or reclassification of such Common Stock.

“ Company ” has the meaning ascribed to such term in the first paragraph of this Warrant.

“ Current Market Price ” shall be determined in accordance with Subsection 3(b).

“ Exercise Date ” has the meaning ascribed to such term in Subsection 2(c).

“ Expiration Date ” has the meaning ascribed to such term in the first paragraph of this Warrant.

“ Issued Warrant Shares ” means any shares of Common Stock issued upon exercise of the Warrant.

“ NASDAQ ” shall mean the Automatic Quotation System of the National Association of Securities Dealers, Inc.

“ Person ” shall mean any individual, firm, corporation, limited liability company, partnership, trust, incorporated or unincorporated association, joint venture, joint stock company, government (or an agency or political subdivision thereof) or other entity of any kind, and shall include any successor (by merger or otherwise) of such entity.

“ Purchase Price ” has the meaning ascribed to such term in the first paragraph of this Warrant.

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“ Warrant ” shall mean this Warrant and any subsequent Warrant issued pursuant to the terms of this Warrant.

“ Warrant Register ” has the meaning ascribed to such term in Subsection 6(c).

2. Exercise of Warrant

(a) Exercise . This Warrant may be exercised, in whole or in part, at any time or from time to time during the period beginning on the date of issue, September 12, 2008 and ending on the Expiration Date, by surrendering to the Company at its principal office this Warrant, with the form of Election to Purchase Shares (the “Election to Purchase Shares”) attached hereto as Exhibit A duly executed by the Holder and accompanied by payment of the Purchase Price for the number of shares of Common Stock specified in such form.

Notwithstanding any provisions herein to the contrary, if the Fair Market Value of one share of Common Stock is greater than the Exercise Price (at the date of calculation as set forth below), in lieu of exercising this Warrant for cash, the Holder may elect to receive shares equal to the value (as determined below) of this Warrant (or the portion thereof being exercised) by surrender of this Warrant at the principal office of the Company together with the properly endorsed Exercise Notice in which event the Company shall issue to the Holder a number of shares of Common Stock computed using the following formula:

(b) Partial Exercise . If this Warrant is exercised for less than all of the shares of Common Stock purchasable under this Warrant, the Company shall cancel this Warrant upon surrender hereof and shall execute and deliver to the Holder a new Warrant of like tenor for the balance of the shares of Common Stock purchasable hereunder.

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(c) When Exercise Effective . The exercise of this Warrant shall be deemed to have been effective immediately prior to the close of business on the Business Day on which this Warrant is surrendered to and the Purchase Price is received by the Company as provided in this Section 2 (the “Exercise Date”) and the Person in whose name any certificate for shares of Common Stock shall be issuable upon such exercise, as provided in Subsection 2(b), shall be deemed to be the record holder of such shares of Common Stock for all purposes on the Exercise Date.

3. Adjustment of Purchase Price and Number of Shares . The Purchase Price and the number of shares of Common Stock issuable upon exercise of this Warrant shall be adjusted from time to time upon the occurrence of the following events:

(a) Dividend, Subdivision, Combination or Reclassification of Common Stock . If the Company shall, at any time or from time to time, (i) declare a dividend on the Common Stock payable in shares of its capital stock (including Common Stock), (ii) subdivide the outstanding Common Stock into a larger number of shares of Common Stock, (iii) combine the outstanding Common Stock into a smaller number of shares of its Common Stock, or (iv) issue any shares of its capital stock in a reclassification of the Common Stock (including any such reclassification in connection with a consolidation or merger in which the Company is the continuing corporation), then in each such case, the Purchase Price in effect at the time of the record date for such dividend or of the effective date of such subdivision, combination or reclassification, and the number and kind of shares of capital stock issuable on such date shall be proportionately adjusted so that the Holder of any Warrant exercised after such date shall be entitled to receive, upon payment of the same aggregate amount as would have been payable before such date, the aggregate number and kind of shares of capital stock which, if such Warrant had been exercised immediately prior to such date, such Holder would have owned upon such exercise and been entitled to receive by virtue of such dividend, subdivision, combination or reclassification. Any such adjustment shall become effective immediately after the record date of such dividend or the effective date of such subdivision, combination or reclassification. Such adjustment shall be made suc