SummaryBarium‐enema studies of the colon undertaken in 1,007 patients with carcinoma of the rectum failed to demonstrate the rectal tumor in 16 per cent of cases, and failed to demonstrate coincidental tumors of the colon in 63 per cent of cases, and failed to demonstrate coincidental tumors of the colon in 63 per cent of patients with such tumors. Additionally there was a 25 per cent incidence of false‐positive findings in the colon.The consequence of this analysis is that we no longer undertake barium‐enema studies of the colon in patients with carcinoma of the rectum confirmed by palpation or proctoscopy. The effect of this is that the surgeon is very aware of the importance of hisperoperative palpation, and palpation has proved to be very much more reliable for detecting coincidental tumors of the colon than preoperative barium‐enema studies.