Effect of 5-Aminosalicylic acid and sulfasalazine in ulcerative colitis was known to suppress the production of prostaglandins and leukotrienes. However, during the oxygenation of arachidonic acid, superoxide and other oxygen moieties are formed which have been implicated in mediators of intestinal mucosal injury. We study the effect of 5-ASA and sulfasalazine on their ability to scavenge superoxide radical and effect on CuZu-SOD, Mn-SOD and catalase in deoxycholic acid induced injured rat colonic mucosa. The result was as follows. 1) DOC and normal saline group showed significant increase in superoxide radical compared with normal saline only group (p<0.005). 2) The experimental groups which were administered 5-ASA and sulfasalazine showed significant decrease in superoxide radical compared with DOC only treated group (p<0.05, p<0,005). 3) Sulfasalazine treated group shovecl increasc in CuZn-SOD compared with DOC onily treated proup (p<0.05). 4) In Mn-SOD, 5-ASA and sulfasalazine treated group showed signnificant increase than that of DOC only treated group (p<0.05). 5) There was no significant difference in the activity of catalase in each experiimiental group.