&NA;In eight years at Cook County Hospital, 42,000 barium enemas, 16,325 proctosigmoidoscopies, and 1207 colonoscopies were performed. All endoscopic procedures were done by the house staff. There were three perforations due to proctosigmoidoscopy, with one death; three perforations due to colonoscopy, with no deaths; and seven perforations due to barium enema, with no survivors. The adjuvant effect of barium sulfate is proposed as the most likely cause for this excessively high mortality in barium‐enema perforation.