Local infusion of urokinase was used in 15 cases of thrombotic occlusion of polytetrafluoroethylene grafts in 10 hemodialyzed patients. The treatment was successful in all patients except one in whom recurring thrombosis occurred because of junctional stenosis at the venous anastomosis. No relevant side effects were observed. Follow-up data show that such treatment can significantly prolong the survival of arteriovenous grafts in hemodialyzed patients with otherwise difficult access to the circulation.