Acute mesenteric arterial occlusion is a curable disease, provided it is diagnosed and treated before irreversible changes occur in the ischemic bowel. Forty patients treated for proven mesenteric arterial occlusion were evaluated retrospectively in an effort to broaden the existing criteria for early diagnosis. Twenty-three patients suffered from mesenteric thrombosis and 17 sustained embolic occlusion of the superior mesenteric artery. The overall mortality rate was 77.5% (31 of 40 patients). Three patients survived without bowel resection. The appearance of acute abdominal pain accompanied by profuse cold sweating in a cardiac patient with apparently normal abdomen, hyperactive bowel sounds, and a history of embolic events should always raise the suspicion of acute mesenteric ischemia and should be verified immediately by mesenteric angiography. A high index of suspicion, aggressive measures for early diagnosis, and early operative treatment are presently the only possibilities to provide a better outcome.