Fifty-seven local transcatheter infusions of low doses of fibrinolytic agents [streptokinase and urokinase] for the treatment of occlusive vascular disease were performed in 49 patients. Thrombosis developed around the infusing catheter in 15 (26%) of these cases. Patients with occlusive vascular disease are at increased risk for the development of thrombosis around indwelling catheters because of the low flow state that exists proximal to the occlusion.