The authors report their treatment of 66 infratentorial arteriovenous malformations (AVM's) in patients aged 5 to 69 years. Sixty-one of them presented with hemorrhage, three with headache, and two with focal neurological deficits. Five patients underwent surgical exploration only, one was treated with ventriculostomy, three had ligation of the AVM feeding arteries, four underwent intraoperative embolization, and two had pontine hematomas removed; complete excision was attempted in 51 patients and accomplished in 47. Twelve of the patients also had aneurysms (nine of which had ruptured). Of this series, 71% had a good result, 14% a poor result, and 15% died. Most of the operative morbidity was due to massive postoperative hemorrhage, probably related to inadequate hemostasis.