We reviewed our experience with 91 patients aged 15 to 40 years with nontraumatic intracerebral hemorrhage (ICH) from January 1991 through December 1994 and found more than ten presumed causes for the nontraumatic ICH in 68 patients (74.7%). The leading two causes were arterial hypertension and ruptured arteriovenous malformations. Most cases of ICH were lobar and putaminal. Of the lobar hemorrhages, 26.5% resulted from ruptured arteriovenous malformations. Of the putaminal hemorrhages, we found 60% resulted from arterial hypertension. Arteriography was performed in 36 patients, and was diagnostic in 23. A history of drug abuse was found in 3 patients. The survival rate was 82.4% at 1 month, 78.0% at 6 months and 76.9% at 1 year. The in-hospital survival rate of all patients in this study was 78.0%. The outcome was determined at one month after hemorrhage. Thirty-two percent of our cases made a good recovery (back to normality), 35% a fair recovery (moderately disabled but independent), 15% a poor recovery (severely disabled and dependent), and 18% died. Arterial hypertensive hemorrhage accounted for almost 30% of our young ICH patients which reminds us of the importance of regular control of blood pressure even in the young adults. Arteriography performed early in the course of nontraumatic ICH in young adults, particularly in lobar hemorrhages, is a valuable adjunct in determining cause. Although the details of history of drug abuse were frequently lacking, physicians should keep this abuse in mind as a possible cause for nontraumatic ICH.