A 45-year-old woman was referred to us with complaint of sudden onset of continuous epigastralgia. She was alert and her blood pressure and pulse rate were in the normal range. Her symptom improved with rest. However, 2 hours later she died of hemorrhagic shock with elevation of abdominal pressure at the toilet. An autopsy revealed a rupture of splenic aneurysm-induced hemoperitoneum. The aneurysm, which was 25mm in diameter, was located in the hilum lienis. The ruptured arterial wall showed thinning of the tunica media, with disappearance of smooth muscle cells and elastic fibers.