A retrospective study of the efficacy of local low-dose intraarterial streptokinase for the treatment of peripheral arterial occlusion was performed in 60 cases. The results of treatment of occlusion of native arterial and arterial graft occlusions were compared. Twenty-two (73%) of 30 cases of arterial occlusion showed complete or partial angiographic resolution, compared with 16 (53%) of 30 cases of arterial graft occlusion. Ten (71%) of 14 patients with venous arterial grafts were successfully treated vs only six (38%) of 16 patients with prosthetic arterial grafts. These results suggest that streptokinase is an effective fibrinolytic agent for the treatment of arterial occlusion and arterial graft occlusion. Its effectiveness in arterial graft obstruction is comparatively low, although patients with venous grafts respond much more favorably than those with synthetic conduits.