The purpose of this prospective study was to determine the value of intraoperative intra-arterial fibrinolytic therapy (IIFT) in patients with acute arterial ischemia as an adjunct to mechanical thromboembolectomy. Sixty-six femoropopliteal or distal acute arterial occlusions were assessed by means of arteriography and Doppler imaging pre- and postoperatively. Two groups of patients were compared: one (n = 35) in which mechanical thromboembolectomy was applied as the single technique and another (n = 31) in which 250,000 IU of urokinase diluted in 250 ml of normal saline solution was instilled at the end of mechanical thromboembolectomy over a 30-minute period with the arterial inflow occluded. Candidates for IIFT were selected according to a nonrandomized method. Intraoperative arteriography showed residual thrombus in 20 (30.3%) patients and unsuspected arterial lesions in 23 (34.8%). Thrombosis recurrence was associated with residual thrombus (p < 0.001) and amputation (p < 0.001). The ankle/brachial index increased significantly (p < 0.05) in the patients who received IIFT (0.88 +/- 0.03) in comparison with those who underwent mechanical thromboembolectomy (0.75 +/- 0.05). Although the percentages of distal revascularization and amputation did not differ significantly between the two groups, quantitatively the results were better in the IIFT group (80.65% success and 9.68% failure) compared to the mechanical thromboembolectomy group (60% success and 22.86% failure). There was no bleeding due to IIFT. Significant variables in our study were diabetes (p < 0.05), the time period of 12 to 24 hours before the surgery (p < 0.05), and the severity of the ischemia in association with rest pain (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)