OBJECTIVE: Spontaneous intracerebral hemorrhage (ICH) in young adults is rare. The purpose of this study was to investigate causes, sites and other factors affecting the prognosis of ICH in young adults aged < or = 40 years. METHODS: We reviewed 39 consecutive patients diagnosed with spontaneous ICH between January 2001 and June 2012. Patients with primary subarachnoid hemorrhage, previously diagnosed brain tumor bleeding, or vascular malformation were excluded. We analyzed the differences in prognostic factors such as hemorrhage location and vascular structural etiology. The outcome was measured using the Glasgow outcome scale (GOS), and a good outcome was defined as a score of 4 or more. RESULTS: We retrospectively evaluated 39 patients (mean age, 33 years; SD = 6.4, range 17 to 40 years). The most common structural etiology was arteriovenous malformation. A statistically significantly higher proportion of patients with good outcomes had a lower initial systolic blood pressure (SBP < or = 160 mmHg, p = 0.036), a higher initial Glasgow coma scale (GCS) (9 or more, p = 0.034), lower cholesterol levels (< 200 mg/dl, p = 0.036), and smoking history (at discharge, p = 0.008; 6 months after discharge, p = 0.019). CONCLUSION: In this study, cryptogenic ICH was the leading cause of spontaneous ICH. A GCS score of 9 or more on admission, a lower serum cholesterol level (< 200 mg/dl), and a lower SBP (< 160 mmHg) predicted a good outcome.