Surgical procedures for Crohn's disease of the small intestine, colon, or rectum were performed in 25 patients who were 65 years of age or older. In elderly patients with primarily small-bowel disease, good results were obtained uniformly by ileal resection and primary intestinal anastomosis. In 15 patients, Crohn's disease involved primarily the large intestine. Subtotal abdominal colectomy with end ileostomy restored health and permitted weight gain in six patients, although three required subsequent proctosigmoidectomy for recurrent rectal symptoms (average interval—18 months). Four patients underwent one-stage proctocolectomy, with one postoperative death and delayed healing of the perineal wound in the three survivors. Major complications frequently followed surgical procedures for suspected sigmoid diverticulitis in elderly patients with unrecognized Crohn's disease of the colon.