The sensitivity of 3 bleeding time techniques to an aspirin-induced defect of platelet function has been assessed in 35 normal volunteers. A carefully standardised Ivy technique was compared with 2 commercial devices for a template bleeding time, the Simplate II and the Thrombolette. The standardised Ivy and the Simplate II were found to have a similar sensitivity; the Thrombolette tended to be less sensitive but the difference was not significant.