In 87 patients (studied on average 1 year after their strokes) and 26 of their first-degree relatives, our specific aim was to assess the prevalence of the following stroke risk factors: hypofibrinolysis, familial hypofibrinolysis, high lipoprotein (a) level, and dyslipidemia. At least 2 months after their strokes (primarily ischemic), 87 patients had measures of lipids and lipoprotein (a); 69 and 67 patients had measures of basal and stimulated fibrinolytic activity, respectively, four new findings were as follows. (1) Hypofibrinolysis was common, with bottom decile-stimulated tissue plasminogen activator activity (the major stimulator of fibrinolysis) in 21% of stroke probands and in 30% of their first-degree relatives, versus 7% of 29 nomolipidemic control subjects (p = 0.09 and 0.026, respectively). (2) The hypofibrinolysis was mediated by top-decile levels of basal plasminogen activator inhibitor activity (the major inhibitor of fibrinolysis), which were observed in 20% of stroke probands and in 21% of their first-degree relatives, versus 8% of 175 nomolipidemic control subjects (p = 0.007 and 0.04, respectively). Mean (SD) basal plasminogen activator inhibitor activity and antigen level were higher in stroke probands (18 +/- 18 U/ml and 35 +/- 31 ng/ml, respectively) than in the 175 normolipemic control subjects (14 +/- 10 [p = 0.002], 28 +/- 34 [p = 0.016]). (3) Levels of basal tissue plasminogen activator antigen, a probable marker for atherosclerosis, were much higher in stroke probands than in the 175 normolipemic control subjects (15 +/- 7.3 ng/ml vs 7 +/- 3.8, p = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)