To test the hypothesis that increased blood pressure and hyperlipidaemia result in changes in the fibrinolytic system, 84 subjects with both hypertension and elevated serum cholesterol levels (the high risk group) were compared with 55 controls matched with respect to age, sex and body mass index (BMI). Plasminogen activator inhibitor (PAI-1), and tissue plasminogen activator (tPA) antigen and activity were measured before and after venous occlusion. In the high risk group, tPA activity was significantly lower both before and after venous occlusion and PAI-1 levels were significantly higher. In a multivariate analysis the triglyceride levels, diastolic blood pressure and cholesterol levels were independently associated with the PAI-1 levels. Diastolic blood pressure was independently and inversely associated with resting tPA activity. We conclude that patients with hypertension and hyperlipidaemia have a reduced activity of the fibrinolytic system, an effect which is unrelated to differences in age, sex, smoking or BMI.