We reviewed our experience with 72 patients, aged 15 to 45 years, who were hospitalized for nontraumatic intracerebral hemorrhages (ICHs) between 1978 and 1985. Evaluation included arteriography in 61 patients. Computed tomography demonstrated 41 lobar, 11 putaminal, four thalamic, four pontine, four intraventricular, two caudate, two midbrain, two cerebellar, one globus pallidum, and one corpus callosum hemorrhage. Forty-three patients, with either progressive neurologic deterioration, arteriovenous malformations (AVMs), or saccular aneurysms underwent surgery. The overall in-hospital survival, including those patients treated medically, was 87.5%. A presumed cause for the ICH was found in 55 (76.4%) patients. The main causes were ruptured arteriovenous malformations (21), hypertension (11), ruptured saccular aneurysms (seven), and sympathomimetic drug abuse (five). Surgical explorations demonstrated a necrotizing angiitis in one patient and arteriovenous malformations in two patients who had negative arteriograms. Young patients with nontraumatic ICHs represent a heterogeneous group. A cause can be established in most patients. Arteriovenous malformations account for less than one third of the hemorrhages in young adults, and other causes should be sought.