The incidence of ischemic colitis in renal transplant recipients approaches 1 percent. The mortality in these patients with ischemic colitis is nearly 70 percent. Immunosuppressive agents have been implicated in the development of ischemic colitis. To study the effect of immunosuppressive agents on ischemic colitis, a 4-cm segment of the colon was devascularized in 27 male Fischer rats. The animals were divided into one control and two treatment groups. One treatment group received methylprednisolone and the other, azathioprine, in doses similar to those of renal transplant recipients. Both experimental groups, either separately or combined, showed significantly greater areas of colonic ischemic changes than did the control group. This study demonstrates that systemic administration of immunosuppressive agents may augment the development of ischemic colitis.