Injuries of small bowel and its mesentery due to blunt trauma are uncommon. Of deaths due to delayed intra-abdominal hemorrhage, mesenteric laceration is a rare cause of hemoperitoneum.A case of a 33-year-old man, who was hospitalized with chest and retroperitoneal trauma after a forklift rollover, is presented. He died 10 days after the incident. At autopsy, he had a massive hemoperitoneum due to a small bowel mesenteric laceration, which was not diagnosed during his clinical course. Microscopic examination of the hematoma around the laceration revealed healing and ruptured pseudoaneurysms in the distal branches of the superior mesenteric artery.