Eighteen patients with chronic renal failure due to primary glomerular disease undergoing conservative treatment (CRF patients) were studied to evaluate whether coagulation and fibrinolytic activity in plasma are enhanced in the patients. We measured plasma levels of coagulation-fibrinolysis parameters including thrombin-antithrombin III complex (TAT) (an index of thrombin formation), alpha 2-plasmin inhibitor (alpha 2 PI)-plasmin complex (alpha 2 PIC) (an indicator of plasmin production) and cross-linked fibrin degradation products (XL-FDP) (an index of fibrinolysis secondary to coagulation). There was no correlation between plasma levels of TAT, alpha 2PIC and XL-FDP and serum creatinine levels in CRF patients. Both fibrinogen and TAT were found to be significantly higher in CRF patients than in normal controls. TAT was negatively correlated with serum albumin or total protein. Antithrombin III (ATIII) activity was significantly lower in CRF patients than in normal controls. CRF patients showed significantly but slightly higher alpha 2 PIC and XL-FDP when compared to normal controls. These results suggest that TAT, alpha 2PIC and XL-FDP are good indicators of coagulation-fibrinolysis even in patients with decreased renal function. Coagulation activity is significantly increased in CRF patients but fibrinolysis secondary to coagulation is only slightly enhanced.