Bleeding assessment tools (BATs) aim to screen and estimate bleeding risk in patients with inherited bleeding disorders. However, the use of BAT as a standardized measure for comparing bleeding in patients on long-term thromboprophylaxis has not yet been validated. We developed a self-administrable BAT to assess bleeding in patients undergoing long-term thromboprophylaxis with aspirin or warfarin. Eligible participants were invited to complete the warfarin-aspirin -BAT (WA-BAT) online. The WA-BAT was readministered a number of weeks later to determine intrarater reliability. The WA-BAT showed substantial intrarater reliability and assesses major and minor bleeding associated with long-term warfarin or aspirin use.