Ten cases of cerebral hemorrhage and one of intraspinal subdural hematoma after thrombolytic therapy are reported. Six patients were treated with streptokinase, four with rt-PA and one with a combination of both drugs. The incidence was 0.5 to 2% and was higher in case of rt-PA therapy (3.7%). In all cases, CT scan showed primary hemorrhage rather than hemorrhagic infarction. Four patients died of stroke. Among the survivors, residual disability was severe in one and mild in five. Only one patient recovered completely. In patients treated with streptokinase, the hemorrhage was probably due to a more than 80% decrease in plasma fibrinogen. In those receiving rt-PA, either excessive dosage (2 cases in our series) or lysis of cerebral microthrombi are thought to be responsible for the hemorrhagic complications. Treatment consists of infection of aprotinin (an anti-fibrinolytic drug), cryoprecipitates with factors V and VIII and protamine sulfate.