Massive acute intestinal ischemia, an intra-abdominal catastrophe, is associated with a high death rate. Only with early diagnosis and prompt aggressive management can this rate be reduced. The key to diagnosis is suspicion followed by intelligent interpretation of physical findings, awareness of the importance of elevated leukocyte count and inorganic phosphate levels and of acidosis, and more liberal use of superior mesenteric angiography in cases of possible intestinal ischemia. A "golden period" exists in which the bowel may be revascularized without tissue loss, so the aim should be to make the diagnosis more often during this period and to restore intestinal blood flow promptly.