A retrospective analysis of 139 patients with brain stem cavernous malformations is presented. The material consists of 41 cases from Bern and Phoenix and 98 further well-documented cases from the literature. Sixty-eight patients were male, 70 were female. The average age was 31.8 + 11.8 years. Sixty-two percent of the cavernous malformations were in the pons, 14% were in the mesencephalon, 12% were in the pontomesencephalic and in the pontomedullary junction, and 5% were in the medulla. Eighty-eight percent of the patients showed evidence of recent or previous hemorrhage, 55% had one hemorrhage. 17% had two hemorrhages, and 17% had three or more hemorrhages. Twelve patients died from a hemorrhage, 5 with the first bleeding and 7 with a rebleeding. The minimum bleeding rate was 2.7% per year and the average rebleeding rate 21% per year and per lesion. Most lesions had a diameter between 10 and 30 mm. Increase in size was observed in 12 of the patients; this corresponds to about 21% when only patients with a follow-up of at least one year are considered. In 93 patients the cavernous malformation was removed operatively while in 30 patients the lesion was not removed. In the group with conservative management at the end of the observation period (up to 25 and 32 years), 66.6% had no or only a slight neurological deficit, 6.7% were moderately disabled, 6.7% were completely dependent, and 20% had died. In the group treated surgically 83.9% had no or only a slight neurological deficit, and 15% were moderately disabled. One patient remained severely disabled, no patient died. The limitations of the retrospective nature of this study are stressed.