Approximately 36% of the US population (more than 50 million people) takes aspirin regularly for heart disease prevention. But what is the right dose? Clinical trials have used doses ranging from 30 mg to 1500 mg/day, and the FDA recommends dosages ranging from 50 mg to 1300 mg/day. A recently published systematic review of 2415 references provided an answer to the question. This review indicates that doses of 75 mg to 81 mg/day provide protection equal to that of higher doses. Doses of 325 mg to 1300 mg/day did not decrease cardiovascular events but did increase the risk of gastrointestinal bleeding. These results agree with those obtained in previously conducted meta-analyses.