Gastrointestinal perforations frequently represent a lethal complication of immunosuppression. Of 325 renal transplant recipients treated with cyclosporin (CsA), 4 patients (1.2%) developed gastrointestinal perforation: 1 from gastric ulcer and 3 from colonic diverticula. All patients underwent operative treatment and all survived without complications. Three patients maintained a well-functioning allograft. In comparison to azathioprine, CsA does not seem to greatly affect the immune response to bacterial infections, thus representing a considerable advantage in the management of serious gastrointestinal complications.