Acacia Research (ACTG) S-3 Shelf registration

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of our report dated March 16, 2006 relating to the financial statements, management's assessment of the effectiveness of internal control over financial reporting and the effectiveness of internal control over financial reporting of Acacia Research Corporation, which appears in Acacia Research Corporation's Annual Report on Form 10-K for the year ended December 31, 2005. We also consent to the reference to us under the heading “Experts” in such Registration Statement. 

/s/ PricewaterhouseCoopers LLP

PricewaterhouseCoopers LLP

Orange County, California 

April 21, 2006