Colon ischemia is expressed in a broad clinical spectrum, from mild, reversible ischemia to intestinal infarction and gangrene. In most cases, the precipitating cause is unknown, and colonic blood flow usually has normalized by the time the patient seeks medical attention. Satisfactory treatment begins with accurate diagnosis, which depends on serial colonoscopic or roentgenographic studies and the exclusion of other disorders that may mimic colon ischemia. Prognosis typically is good, and most patients require only supportive care with close follow-up. More aggressive therapy, including surgery, is indicated in patients who early in their course develop massive bleeding, perforation, or signs of fulminant colitis or who subsequently develop symptomatic strictures or persistent symptoms of colitis.