An 84-year-old man was admitted to our hospital because of blood in the stool. He had previously undergone a subtotal colectomy and ileostomy with a mucous fistula of the sigmoid colon because of a large bowel hemorrhage of unknown origin. Five years later, a minor hemorrhage developed in the remnant rectum. The clinical history, colonoscopic findings, and the histology of the diverted colon specimens were suggestive of diversion colitis. Treatment was initiated with short-chain fatty acid enema, but slight blood loss through the stool continued;thus, the patient was administered 5-aminosalicylic acid (5-ASA) enema. Subsequently, his symptoms and endoscopic findings improved. 5-ASA enema appears to be both safe and effective in the treatment of diversion colitis following intestinal tract surgery.