Colonoscopy is routinely performed with conscious sedation. We wanted to determine if colonoscopy can be successfully completed without sedation and to assess patient tolerance and acceptance. One hundred nine consecutive patients undergoing colonoscopy were examined. The risks and benefits of colonoscopy with or without sedation were explained in a standard format. Patients were then given the option of having colonoscopy without premedication. After the procedure, as well as 2 to 5 days later, patients rated on an analog scale (0, no pain; 5, severe) the severity of pain and willingness to undergo colonoscopy in the future without sedation. Eighty patients underwent colonoscopy without prior sedation. Only 6% (n=5) required sedation to complete the examination. When questioned, 5% experienced no pain, 41% slight or mild pain, 34% moderate pain, and 20% severe pain. Seventy-three percent (n=58) were willing to undergo repeat colonoscopy without sedation, 10% (n=8) were undecided, and 18% (n=14) would request sedation. Pain severity was a strong predictor (p=0.001) of future sedation preference. Colonoscopy without sedation may be completed successfully in most patients and does not undermine many patients' willingness to undergo a similar procedure in the future. Sedation by choice is more cost-effective, may be safer, and should be offered as an alternative to routine intravenous sedation.