Relationships between exercise and various measures of hemostasis have been reported throughout the last 70 years. As hemostatic mechanisms have been implicated in disease and have been manipulated in therapy, the relationship to exercise and endurance training demands attention. Studies to date, however, have often been discordant and confusing. This review summarizes and analyzes the literature with regard to the effects of exercise and training on measures of coagulation platelet function, and fibrinolysis in normal human subjects. Although platelet count, coagulation factor VIII activity, and some measures of coagulation activity of the blood may increase after exercise, fibrinolytic potential also increases and there is no convincing evidence of clot formation or change in the overall balance of hemostatic mechanisms with exercise. Relatively few data exist on the effects of endurance training on hemostatic mechanisms. Although platelet function and the response to exercise of some measures of fibrinolytic and coagulation mechanisms may be modified, more standardized, quantitative data obtained by state of the art methods are needed before definitive conclusions are possible. Future studies will benefit from application of more standardized techniques of exercise research as well as attention to closer control of factors known to affect hemostatic mechanisms.