In the University Cantonal Hospital in Basel, 34 intraventricular hemorrhages were diagnosed by computer tomography from 1981 to 1990. The most frequent cause of bleeding into the ventricular system (35.3%) was rupture of an aneurysm, followed by hypertensive hemorrhages (23.5%). The cause of bleeding into the ventricular system could not be found in 20.6% of the cases investigated. The hemorrhage was present in all ventricles in 13 cases. A ruptured aneurysm was responsible for this in five patients. The hemorrhage was found in two and three ventricles in 11 cases. Only one ventricle was filled with blood in 10 cases; this was due to hypertensive hemorrhage in four patients. Besides open and enclosed ventricular drainage, aneurysm clipping was carried out in six cases, osteoplastic craniotomy in 12 cases and bore hole trepanation in four cases, depending on the underlying disease responsible for bleeding into the ventricular system. We were able to observe restitution of complete functional integrity at the follow-up examination one year later in eight cases (23.53% of all patients). Neurological deficits were shown at follow-up in 10 cases (= 29.41%). In our patients, the mortality was 47.1% (= 16 patients).