Abstract The effect of chronic physical exercise on hemostasis and thrombosis was studied in 35 long-distance runners who took part in an 1.000-km race lasting for 20 days and divided into daily portions of about 50 km. The following parameters were measured on the day before the race (day 0) and on days 1, 3, 6, 8, 11, and 19: factor VII activity, fibrinogen, t-PA, PAI-1, plasminogen, antiplasmin, D-dimers, and thrombinantithrombin-III complexes (TAT). During the race there was a rapid drop of factor VII and a continuous increase of fibrinogen. t-PA rapidly increased on day 1 and returned to baseline values on days 6 and 8. PAI-1 and antiplasmin were not influenced. Plasminogen decreased significantly on day 3 and returned to initial levels on days 11 and 19. D-Dimers continuously increased reaching the maximum levels on day 19. TAT levels were only significantly increased on day 19.