A 57-year-old man with cirrhosis presented to the emergency department with acute abdominal pain that had been present for 1 day. On physical examination, his abdomen was tender to palpation over the epigastrium and lower abdomen, with rebound tenderness and guarding. Laboratory studies revealed a white-cell count of 8400 per cubic millimeter (normal range, 4000 to 11,000) and a serum lactate level of 18.4 mmol per liter (normal range, 0.5 to 2.2). Computed tomography revealed pneumatosis intestinalis. Because of concern about ischemic bowel, the patient underwent emergency laparotomy. During surgery, the jejunum and ileum were noted to be cyanotic and congested, and the mesenteric veins contained visible air with venous pulsation . No bowel was resected, because bowel peristalsis was present. Mesenteric ischemia can be caused by acute arterial or venous thromboembolism or by decreased blood flow to the splanchnic vessels, usually owing to hypotension in patients with atherosclerotic disease. If a patient presents with acute peritonitis, urgent laparotomy is indicated to evaluate for infarcted bowel. After surgery, the patient was admitted to the intensive care unit and received vasopressors, fluids, antibiotic agents, and low-molecular-weight heparin, and he had a full recovery.