Background: Colonoscopy is considered a painful procedure requiring routine intravenous sedation. We investigated whether unsedated colonoscopy causes more discomfort than barium enema. Methods: Procedure-related discomfort was determined in 100 consecutive patients undergoing colonoscopy without premedication and in an equal number of patients referred for sigmoidoscopy and barium enema. All patients underwent such examinations for the first time and had no history of previous bowel surgery. During colonoscopy, sedation was offered if significant pain or discomfort occurred. Results: In patients without stenosis and with satisfactory preparation, the completion rate of colonoscopy was 95%. Five percent of all patients undergoing endoscopy required sedation. On an analog scale ranging from 1 to 9, patients undergoing colonoscopy and barium enema reported similar ratings for procedure related discomfort (3.2 ± 1.7 and 3.1 ± 1.9) and for discomfort caused by bowel preparation (3.2 ± 2.1 and 3.1 ± 1.8). Eighty-seven percent of all patients undergoing colonoscopy stated that they would prefer no premedication in the event of repeated examinations. Conclusions: Colonoscopy with sedation on demand does not cause more discomfort than barium enema and will be accepted by the vast majority of patients undergoing this procedure. (Gastrointest Endosc 1996;44:177-80.)