&NA;A 57‐year‐old man administered an enema to himself, preparatory to intravenous pyelography. He left after the films were taken and could not be reached when retroperitoneal emphysema was detected. He was located 12 days later and found in good health. Abdominal x‐ray films and rectosigmoidoscopy were normal. The patient refused further investigations. It is assumed that a small perforation occurred at the rectosigmoid junction during the self‐administration of the enema. This assumption is borne out by the pattern of air distribution. The total absence of complaints and physical signs is unusual, although not unique; similar cases have been reported previously. The cause of such injury is mechanical, since the high pressures necessary to rupture the rectum are not usually attained in ordinary enemas. Caution is called for in intrarectal instrumentation, especially in older patients.