The template bleeding time is a measure of platelet participation in primary hemostasis. Aspirin alters platelet function through interference with prostaglandin biosynthesis. In many individuals, aspirin will consistently prolong the bleeding time. Despite this observation, normal individuals rarely develop a bleeding disorder. This prompted us to investigate the influence of technical variables on the prolongation of the bleeding time by aspirin. Both direction of incision and venostasis influenced the prolongation of the bleeding time by aspirin. A horizontal incision with venostasis produced the most pronounced prolongation, while a vertical incision without venostasis didn't prolong the bleeding time despite the characteristic changes in platelet aggregation and release. These studies suggest that the influence of aspirin on the template bleeding time is dependent on technical variables and is minimal in the normal subject.