This statement summarizes the recommendation of the third U.S. Preventive Services Task Force (USPSTF) for aspirin for the primary prevention of cardiovascular events, as well as the supporting scientific evidence. The complete information on which this statement is based, including evidence tables and references, can be found in a companion article in this issue. Copies of this document, the summary of the evidence, and the systematic evidence review can be obtained through the USPSTF Web site (http://www.ahrq.gov/clinic/uspstfix.htm) and in print through the Agency for Healthcare Research and Quality Publications Clearinghouse (800-358-9295).