Background/Aims: Colonic ischemia is recognized as the most common vascular disorder of the intestines in the elderly. The severity of the disease may vary considerably with the prevalent benign transient forms, being amenable to conservative treatments and the severe gangrenous forms, requiring surgery. Correct diagnosis is usually made after the ischemic episode is over and colonic ischemia is frequently misdiagnosed. The aim of this study is to identify the clinical patterns and prognostic factors of ischemic colitis. Methods: We found 60 patients with nonoccusive ischemia of the large intestine, We analyzed age, sex, symptoms, signs, associated disease, location, endoscopy, hematologic, histologic, radiologic finding and treatment, retrospectively. Results: The mean age was 60.2±6.3 years. The most common symtoms were abdominal pain or bloody diarrhea. The most common sign was diffuse abdominal tenderness. The most common hematologic findings were anemia and leukocytosis. Associated medical illnesses were diabetes, rhematoid arthritis and cerebrovascular accident, et al. Both computed tomography (CT) and endoscopy were useful diagnostic tools. The most common involved site was sigmoid colon. 46 patients were treated conservatively and 14 patients were managed surgically. Conclusions: Male gender, those with rebound tenderness, severe anemia, right or total colon involvement as well as rheumatoid arthritis had a poor prognosis. Both CT and endoscopy were useful in predicting prognosis. (Korean J Gastrointest Endosc 2001;22:76 - 82)