Idiopathic segmental infarction of the greater omentum seldom enters into the differential diagnosis of acute abdominal pain, and diagnosis is usually not made until laparotomy. A preoperative clue to the diagnosis may be the lack of systemic gastrointestinal symptoms in the presence of impressive abdominal findings. Intraoperative clues are serosanguineous peritoneal fluid but normal appendix, distal small bowel, and mesentery. In this setting, careful examination of the omentum through the initial incision is recommended. Once identified, the infarcted omentum should be completely excised to prevent formation of adhesions and possible sepsis. In the case reported here, the serendipitous discovery of edematous omentum prompted a thorough--but technically difficult--exploration of the greater omentum, which eventually led to the correct diagnosis.