Acute effects of moderate alcohol consumption on fibrinolytic factors were investigated in 8 healthy middle-aged men (between 45 and 55 years) in a carefully controlled study. Alcohol consumption comprised two glasses of red wine during dinner and two glasses of Dutch gin in combination with a snack during the evening (40 g of alcohol in total). During the control treatment corresponding volumes of mineral water were consumed. Blood samples were drawn before dinner (around 15:00), 1 h after dinner (around 19:00), 1 h after the snack (around 23:00) and the next morning (around 08:00). PAI activity was increased by 230% (p<0.001) after alcohol consumption at the late evening measurement. PAI-1 antigen levels, however, were not significantly affected. The specific activity of PAI (activity/antigen quotient) was significantly increased by alcohol consumption at all three times of measurement after dinner. As a consequence tissue-type plasminogen activator (t-PA) activity was reduced by up to 95% (p<0.001), around 23:00. Levels of t-PA antigen, on the other hand, were increased after alcohol consumption (up to +42%, p<0.01). No effects of alcohol consumption on the urokinase plasminogen activator (u-PA) system were observed. We conclude that shortly after moderate alcohol consumption both t-PA antigen and PAI activity levels are increased, resulting, however, in a decreased activity of t-PA. Increased PAI activity persists after an overnight fast.