During a survey of four month’s duration the following parameters were determined in 43 healthy blood donors (22 males, 21 females; mean age 29 years /20 – 49/): plasminogen activity, plasminogen concentration, α2-antiplasmin (α2-AP) activity, α2-AP concentration, tissue type plasminogen activator (t-PA) activity, t-PA concentration, plasminogen activator inhibitor – I (PAI-I) activity, AT III activity, AT III concentration and heparin cofactor II (HC II) activity. Normal values including standard deviation (x ± 2s) were: plasminogen activity: 96.3 % (65.9 – 126.8), plasminogen concentration: 12.2 mg/dl (7.7 – 16.8), α2-APactivity: 99.9 % (83.8 – 116), α2-APconcentration: 108.1% (84.5 -131.8), t-PA activity: 0.85 IU/1 (0.0 – 1.92), t-PA concentration: 10.3 ng/ml (2.5 – 18.1), PAI-I activity: 15.2 AU/ml, AT III activity: 111.4 % (87.8 – 134.9), AT III concentration: 31.6 mg/dl (24.2 – 39.1) and HC II activity: 110.7 % (81.4 – 140.0). Concerning plasminogen values no sex related difference could be stated. Women who were smokers and used oral contraceptives tended to present elevated t-PA activity levels due to a lower activity of PAI-I, although this tendency was not significant. Determining concentration and activity of components in the fibrinolytic system plays an important part in the diagnosis, therapy and prognosis of thrombophilic disorders.