We sought to compare the risk of hemorrhage due to the low (<100 mg), moderate (100 to 200 mg), and high (>200 mg) doses of aspirin (acetylsalicylic acid [ASA]) in 192,036 patients enrolled in 31 clinical trials. Despite substantial differences in the reporting patterns of bleeding complications, low-dose ASA was associated with the lowest risk, and moderate doses caused a relatively high hemorrhagic event rate, especially with regard to minor, gastrointestinal, and total bleeding, and stroke. These findings should be considered when using combination antiplatelets, anticoagulant therapy, or both, with ASA, especially with the daily dose of >100 mg.