The authors have reviewed 80 cases of subcortical cerebral hemorrhage, in all of which intraoperative examinations during craniotomy or autopsies were performed. Cases involving trauma and aneurysm were excluded from the study. The diagnosis of subcortical hemorrhage was made by plain computed tomography in all cases. The most common cause of hemorrhage was vascular malformation (68%; 56 cases), in 20 (36%) of which angiographically occult vascular malformations were noted. Hypertension was present in 23 (29%) of 80 cases but was the cause of hemorrhage in only 9 cases (11%). Hypertension was present in 6 (30%) of 20 angiographically occult vascular malformations, all of which were in patients under 65 years. In 12 (75%) of 16 cases of angiographically occult vascular malformations, prolonged high-dose delayed-contrast computed tomography and magnetic resonance imaging were able to provide definite diagnostic information. We recommend that patients with subcortical cerebral hemorrhage, especially those under age 65, with or without hypertension, be carefully examined by prolonged high-dose delayed contrast computed tomography and magnetic resonance imaging for the presence of angiographically occult vascular malformations causing hemorrhage.