Prospectus Supplement Filed pursuant to Rule 424(b)(3)
Registration No. 333-138257

PROSPECTUS SUPPLEMENT NO. 29

DATED DECEMBER 8, 2008

(To Prospectus Dated November 17, 2006)

BIOVEST INTERNATIONAL, INC.

18,000,000 Shares of Common Stock

This prospectus supplement supplements information contained in, and should be read in conjunction with, that certain Prospectus, dated November 17, 2006, of Biovest International, Inc. (the “Company”) as supplemented by Supplement No. 28 thereto dated November 10, 2008, Supplement No. 27 thereto dated November 3, 2008, Supplement No. 26 thereto dated September 29, 2008, No. 25 thereto dated August 14, 2008, Supplement No. 24 thereto dated August 1, 2008, Supplement No. 23 thereto dated July 14, 2008, Supplement No. 22 thereto dated June 6, 2008, Supplement No. 21 thereto dated May 16, 2008, Supplement No. 20 thereto dated April 17, 2008, Supplement No. 19 thereto dated February 15, 2008, Supplement No. 18 thereto dated February 7, 2008, Supplement No. 17 thereto dated January 28, 2008, Supplement No. 16 thereto dated January 22, 2008, Supplement No. 15 thereto dated December 31, 2007, Supplement No. 14 thereto dated December 31, 2007, Supplement No. 13 thereto dated November 2, 2007, Supplement No. 12 thereto dated October 18, 2007, Supplement No. 11 thereto dated September 11, 2007, Supplement No. 10 thereto dated August 15, 2007, Supplement No. 9 thereto dated June 29, 2007, Supplement No. 8 thereto dated June 14, 2007, Supplement No. 7 thereto dated May 15, 2007, Supplement No. 6 thereto dated April 19, 2007, Supplement No. 5 thereto dated March 28, 2007, Supplement No. 4 thereto dated February 14, 2007, Supplement No. 3 thereto dated January 19, 2007, Supplement No. 2 thereto dated December 29, 2006 and Supplement No. 1 thereto dated December 14, 2006. This prospectus supplement is not complete without, and may not be delivered or used except in connection with, the original Prospectus and Supplement Nos. 1 through 28 thereto. The Prospectus relates to the public sale, from time to time, of up to 18,000,000 shares of our common stock by the selling shareholders identified in the Prospectus.

The information attached to this prospectus supplement modifies and supersedes, in part, the information in the Prospectus, as supplemented. Any information that is modified or superseded in the Prospectus shall not be deemed to constitute a part of the Prospectus, except as modified or superseded by this prospectus supplement or Prospectus Supplement Nos. 1 through 28.

This prospectus supplement includes the attached Form 8-Ks filed on December 1, 2008 and December 8, 2008, as filed by us with the Securities and Exchange Commission.

We may amend or supplement the Prospectus from time to time by filing amendments or supplements as required. You should read the entire Prospectus and any amendments or supplements carefully before you make an investment decision.

The Securities and Exchange Commission and state securities regulators have not approved or disapproved these securities or determined if this Prospectus Supplement (or the original Prospectus dated November 17, 2006, as previously supplemented) is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is December 8, 2008.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): December 2, 2008

BIOVEST INTERNATIONAL, INC.

(Exact name of Registrant as Specified in its Charter)

324 South Hyde Park Avenue, Suite 350

Tampa, FL 33606

(Address of Principal Executive Offices; Zip Code)

Registrant’s telephone number, including area code: (813) 864-2554

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

BIOVEST INTERNATIONAL, INC.

FORM 8-K

On December 2, 2008, Steven R. Arikian, M.D. resigned from all positions with the Company including as Chief Executive Officer, President and a Director.

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Signature

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunder duly authorized.

Date: December 8, 2008

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 24, 2008

BIOVEST INTERNATIONAL, INC.

(Exact name of Registrant as Specified in its Charter)

324 South Hyde Park Avenue, Suite 350

Tampa, FL 33606

(Address of Principal Executive Offices; Zip Code)

Registrant’s telephone number, including area code: (813) 864-2554

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

BIOVEST INTERNATIONAL, INC.

FORM 8-K

On November 24, 2008, Robert D. Weiss resigned as a director of the Company.

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Signature

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunder duly authorized.

Date: December 1, 2008

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