We have investigated fibrinolytic parameters in 33 patients with peripheral arterial occlusive disease (PAOD) before and 6, 24, and 48 hours after percutaneous transluminal angioplasty (PTA) as well as in 35 gender-matched healthy controls, whose mean age was not significantly different from the mean age of the patients. PAOD patients had significantly higher plasma levels of t-PA antigen (12.0+/-4.9 vs. 9.2+/-5.5 ng/ml), PAI-1 antigen (34.8+/-22.1 vs. 27.2+/-23.6 ng/ml), PAI-1 activity (10.0+/-6.5 vs. 8.0+/-8.0 U/ml), PCI (188.2+/-55.6 vs. 134.1+/-75.5% as compared with normal human plasma), and fibrinogen (420.2+/-92.6 vs. 261.9+/-32.7 mg/dl) as compared with controls. After angioplasty, fibrinolytic parameters and fibrinogen levels increased, reaching higher than preintervention levels 24 and 48 hours after the intervention. Six months after initially successful PTA, restenosis was demonstrated in 14 out of 33 patients (42%). Patients with late restenosis had significantly higher levels of PAI-1 activity 24 and 48 hours after PTA, as compared with patients with late patency (24 hours: 16.1+/-8.0 vs. 10.0+/-7.4; 48 hours: 16.5+/-7.9 vs. 12.0+/-7.0; p<0.05 for both time points). The results suggest that impaired fibrinolysis early after PTA might be a cause or marker of a disturbed repair process of vascular injury, leading to restenosis.