Local therapeutic fibrinolysis is considered an efficient and established treatment for peripheral arterial occlusive disease. The introduction of newer fibrinolytics along with the development of interventional catheterization techniques have extended its use to previously untreated events such as cerebrovascular occlusions. Between 1989-1991 six patients with basilar and/or middle cerebral artery thrombosis were treated at the University Hospital, Basel, by superselective local intraarterial infusion of 400,000 U/h urokinase for 1-2 hours. Two of four patients with basilar artery occlusion showed complete remission one year after the intervention. The third showed no neurological improvement despite angiographic recanalization, and 48 h later suffered a fatal brainstem haemorrhage, while the fourth did not recover from coma and succumbed. Both patients with occlusion of the middle cerebral artery showed complete recanalization, but one had complete and the other partial neurological remission. Signs of slight systemic fibrinolysis were present but never attained the intensity of systemic therapeutic fibrinolysis as the antiplasmin and fibrinogen values showed. In summary, local therapeutic fibrinolysis contributes to the reduction of mortality and to remission of symptoms in occlusions of basilar artery, and offers some advantage in occlusions of the middle cerebral artery. A definite benefit from the latter will be proved only through large-scale randomized trials. The indication for local therapeutic fibrinolysis for thromboses of cerebral arteries requires a careful benefit-risk evaluation, an experienced angiography team and a special infrastructure for computed tomography and digital subtraction angiography.