SummaryThe collagen fibrils of the subendothelium, the blood How rate, the factor VIII complex and a binding site in the platelet membrane are some of the essential factors contributing to platelet adhesion to the damaged vascular wall.Adhering platelets release their content: ADP, 5HT, factor 4…as well as a factor which induces smooth muscle cell proliferation.Saturated fatty acids and cholesterol make platelets more responsive to the circulating agents (ADP, adrenaline, thrombin) and to collagen. The interest of common and new methods for the study of platelet function is briefly discussed.