The aim of this study was to investigate the relationship between various vascular factors and mucosal blood flow that lead to the development of ischemic colitis. Thirty rats were divided into three groups of ten rats each. In group A rats, the marginal artery of the left colon was ligated at two points to induce colonic Ischemia. In group B rats, sennoside (Alosenn®) 20mg/day was administered orally for 3days to induce colonic peristalsis. In group C rats, the marginal artery was ligated and then sennoside, 20mg/day, was given orally for 3days to induce both colonic Ischemia and peristalsis. In all rats, the mucosa of the colon was observed by endoscope, and blood flow was measured with a flow-meter. In group A, two rats showed redness of the colonic mucosa and one had an ulcer in the ligated segment. The mean mucosal blood flow in the region where ligation was performed, was less than half that in the region where the artery ligation was not performed. Among the Group B rats, one showed redness after sennoside administration. However, there was no significant change in mucosal blood flow after administration. All ten Group C rats showed mucosal redness and four rats had ulcers in the area supplied by the ligated artery. The mean mucosal blood flow was significantly decreased in the region of mucosal redness, and was even lower in the mucosa surrounding the ulcer compared to the normal mucosa. Ligation of the marginal artery of the colon led to a decrease in mucosal blood flow and enhancement of bowel peristalsis by administration of a laxative induced ischemic colitis, leading to a further decrease in mucosal blood flow.