The relationships between plasminogen activator inhibitor (PAi) activity and lipoprotein(a) [Lp(a)] and insulin, testosterone, 17 beta-estradiol, and testosterone binding globulin (TEBG) were assessed in 42 myocardial infarction male patients and 74 healthy controls. Patients had higher levels of insulin than did controls (87 +/- 30 vs. 75 +/- 28 pmol/L, respectively; P < 0.04), and no differences were found in levels of PAi activity, testosterone, 17 beta-estradiol, and TEBG. Lp(a) levels greater than 0.3 g/L were more frequent in patients than in controls (P < 0.002). In all subjects, PAi activity levels were significantly and positively correlated with body mass index (r = 0.20, P < 0.05), triglycerides (r = 0.38, P < 0.0001), and insulin (r = 0.27, P < 0.005) and were negatively correlated with testosterone (r = -0.28, P < 0.005) and TEBG (r = -0.42, P < 0.001). Stepwise multiple regression analysis showed triglyceride, insulin, and TEBG levels to be significantly related to PAi activity. No significant correlations were found between Lp(a) levels and all hormonal variables studied and between Lp(a) and PAi activity (r = -0.06, P < 0.58). These results suggest that TEBG is significantly and independently related to PAi levels.