Summary A 27-year-old male commercial diver developed massive mesenteric venous thrombosis following a dive. Symptoms at presentation included abdominal pain and diarrhea. A severe upper gastrointestinal bleed developed. Exploratory laparotomy demonstrated 130 cm of infarcted small bowel. The pathophysiologic events in decompression sickness predispose to vascular obstruction and venous infarction. This patient had a past history of possible thrombophlebitis and pulmonary embolism associated with diving but no identifable coagulopathy.