AIM: To determine the clinical, analytical and endoscopic factors related to ischemic colitis (IC) severity. METHODS: A total of 85 patients were enrolled in a retrospective study from January 1996 to May 2004.There were 53 females and 32 males (age 74.6 ± 9.4 years, range 45-89 years). The patients were diagnosed as IC. The following variables were analyzed including age, sex, period of time from the appearance of symptoms to admission, medical history, medication, stool frequency, clinical symptoms and signs, blood tests (hemogram and basic biochemical profile), and endoscopic findings. Patients were divided in mild IC group and severe IC group (surgery and/or death). Qualitative variables were analyzed using chi-square test and parametric data were analyzed using Student's t test (P ＜ 0.05).RESULTS: The mild IC group was consisted of 69 patients (42 females and 27 males, average age 74.7 ±12.4 years). The severe IC group was composed of 16 patients (11 females and 5 males, average age of 73.8 ± 12.4 years). One patient died because of failure of medical treatment (no surgery), 15 patients underwent surgery (6 after endoscopic diagnosis and 9 after peroperatory diagnosis). Eight of 85 patients (9.6%) died and the others were followed up as out-patients for 9.6 ± 3.5 mo. Demographic data, medical history, medication and stool frequency were similar in both groups (P ＞0.05). Seriously ill patients had less hematochezia than slightly ill patients (37.5% vs 86.9%, P = 0.000). More tachycardia (45.4% vs 10.1%, P = 0.011) and a higher prevalence of peritonism signs (75% vs 5.7%, P = 0.000) were observed in the severe IC group while the presence and intensity of abdominal pain were similar between two groups. Two patients with severe IC had shock when admitted. Regarding analytical data, more seriously ill patients were found to have anemia and hyponatremia than the mildly ill patients (37.5% vs 10.1%, P = 0.014 and 46.6% vs 14.9%, P = 0.012, respectively). Stenosis was the only endoscopic finding that appeared more frequently in seriously ill patients than in slightly ill patients (66.6% vs 17.3%, P = 0.017).CONCLUSION: The factors that can predict poor prognosis of IC are the absence of hematochezia, tachycardia and peritonism, anemia and hyponatremia and stenosis.