Twelve patients with arterial occlusions demonstrated by angiography were treated using intraarterial "low dose" streptokinase delivered to the site of occlusion via a 5 French catheter. The catheter was embedded at the site of arterial occlusion if possible, but if not, was placed immediately proximal to the occlusion. Streptokinase was infused at 5,000 U/hr in a volume of about 50 ml using an arterial infusion pump. The technique was applied to vessels of the upper and lower extremities as well as the renal arteries. Of 12 patients infused, 11 had successful thrombolysis. No hemorrhagic complications were encountered. This technique is extremely promising as a method of treatment of thromboses of recent origin, especially in the poor operative candidate, and for angioplasty-related thromboses.