The investigation of the influence of short‐term exhaustive exercise on platelet function (aggregation andin vivoactivation) in young athletes competing in different sports was the purpose of the study. In 15 athletes aged 15 to 22 years plasma beta‐thromboglobulin and platelet aggregation were estimated before, 3 minutes, and 30 minutes after short‐term exhaustive exercise. The exercise led to an increase ofin vivoplatelet activation that was manifested in an increase of plasma beta‐thromboglobulin level 3 minutes after exercise. Platelet aggregation—the initial as well as adrenaline‐and adenosine diphosphate (ADP)‐induced—was not significantly different from the resting value at this time, but 30 minutes after exercise the total adrenaline‐and ADP‐induced platelet aggregation was decreased. The findings indicate the complex influence of exercise on hemostasis that is of importance not only for patients with atherosclerotic complications, but also for active athletes.