The outcome of 72 direct intra-arterial urokinase infusions was studied prospectively. Thirty four were performed for native arterial occlusion and 38 for bypass graft occlusion; the immediate success rates were 67.5 and 84% respectively. The overall incidence of complications was 26%. Median follow-up was 36 (range 1-60) months. Seventeen patients (27%) died during follow-up; nine (14%) required a major amputation. Among patients with native arterial occlusion, 29% had no adjunctive procedure after thrombolysis; of these patients, 85% remained patent at a median of 21 (range 3-42) months. Among bypass occluded patients, only two (6%) had no lesion revealed after successful lysis; both bypasses remain patent at 54 and 58 months respectively. For patients treated with balloon angioplasty immediately after successful thrombolysis, 62% with native arterial occlusion remained patent at a median of 39 (range 2-60) months, whereas only 27% of bypass occlusion patients were patent at a median of 11 (range 2-40) months. Of patients requiring a surgical procedure after thrombolysis, 23 new bypasses (15 vein, eight prosthetic) were placed (nine in native arterial occlusion patients, 14 in bypass occlusion patients). In addition, there were 15 other surgical procedures, including six thrombectomies, four vein patch angioplasties, four vein jump grafts and one endarterectomy. The primary and secondary patencies for the 15 new vein bypasses placed were 81 and 88% respectively at a median follow-up of 36 months. Good immediate results were experienced with urokinase thrombolysis for peripheral arterial and graft occlusions. However, multiple adjunctive procedures were required to maintain patency.(ABSTRACT TRUNCATED AT 250 WORDS)