Gastrointestinal manifestations of chronic granulomatous disease of childhood include granulomatous inflammatory bowel disease. Severe colitis and perirectal disease developed in a 12-year-old boy with chronic granulomatous disease while he was receiving interferon gamma therapy. The boy had a deficiency of the 22 kd light chain of the cytochrome b heterodimer. After conventional medical therapy proved to be ineffective, a rapid clinical response was obtained to cyclosporine.