Malignant fibrous histiocytoma (MFH) is an uncommon soft-tissue sarcoma that occurs primarily in the extremities and rarely involves the retroperitoneum and abdomen. A 63-year-old man was admitted to the emergency room because of epigastric pain. Computed tomography revealed a large heterogeneous enhanced mass originating from the omentum with hemoperitoneum. The patient underwent laparoscopic omental mass excision and hematoma evacuation. Histological examination of the resected tumor revealed MFH. This case was therefore omental MFH presenting with hemoperitoneum. (Gut Liver 2010;4:241-244)