AMENDMENT TO PATENT TRANSFER AGREEMENT

Exhibit 10.1

AMENDMENT TO PATENT TRANSFER AGREEMENT

THIS IS AN AMENDMENT, dated as of April 27, 2007, to that certain PATENT TRANSFER AGREEMENT dated as of May 11, 2005 (the “Patent Transfer Agreement”) by and between Bayer Schering Pharma AG, a German corporation having its principal place of business at Müllerstraße 178, 13353 Berlin, Germany (hereinafter referred to as “BSP”) and Acusphere, Inc., a Delaware corporation having its place of business at 500 Arsenal Street, Watertown, MA 02472, USA (hereinafter referred to as “Acusphere”)

WHEREAS, BSP (formerly acting under the name Schering Aktiengesellschaft) and Acusphere entered into the Patent Transfer Agreement on May 11, 2005, pursuant to which certain patent rights were transferred from BSP to Acusphere;

WHEREAS, under the Patent Transfer Agreement Acusphere will be obligated to make a final payment of $3,000,000 to BSP on May 11, 2007;

WHEREAS, Acusphere wishes to defer payment of such final payment and BSP is willing to agree to a deferral on the terms set forth herein;

NOW, THEREFORE, in consideration of the mutual covenants contained herein the parties hereto agree as follows:

1.               Notwithstanding anything to the contrary contained in the Patent Transfer Agreement, rather than the second $3,000,000 payment payable under Section 3.1 of the Patent Transfer Agreement, Acusphere shall instead pay BSP a total of $3,500,000 as follows:

a.               $1,500,000 on or before fifteen days after the execution of the Amendment;

b.              $1,000,000 on or before fifteen days after May 11, 2008; and

c.               $1,000,000 on or before fifteen days after May 11, 2009.

2.               In all other respects, the Patent Transfer Agreement shall remain in effect as executed.

IN WITNESS WHEREOF, the parties have executed this Amendment to Patent Transfer Agreement as of the date first above written.

ACUSPHERE, INC.

BAYER SCHERING PHARMA AG