Background:Colonoscopy is usually performed with sedation. Little is known about patient(pt) tolerance of the procedure without medication.We performed a prospective, randomized trial of sedated vs. unsedated colonoscopy. To our knowledge, this is the first study of this issue in an academic setting with trainees performing exams. Methods:Consecutive outpatients were offered the study. Patients were randomized to receive sedation or to begin the procedure without sedation; medication was given upon request. A brief survey of symptoms(sx) was completed by all patients. After the exam, patients graded their satisfaction from 0-10. Recovery times were recorded. Exams were performed by senior fellows (experience range 108-696 exams) or an attending (24%). Results:142/384(37%)of patients agreed to enroll. 45% randomized to sedation (S); 55% to no sedation (NS). There was no difference between groups in terms of prior colonoscopy, age, or gender. There was no difference in procedure times (S=27 minutes, NS= 26.5 minutes). Median satisfaction ratings were 10 (S) vs. 9 (NS), p=0.004. Recovery times were significantly shorter in the NS group, 16.5 minutes vs.55 minutes, p=0.0001. Of those randomized to NS, 23% required sedation to complete the exam. 71% of patients in the NS group who had had a prior colonoscopy stated they would undergo the procedure again without sedation. Sedation, but not sx or endoscopist experience, correlated with satisfaction. Endoscopist experience did not correlate with failure of NS exam. Pts with sx consistent with IBS were significantly less likely to complete the exam without sedation(p=0.04);10/10 of such pts randomized to NS required sedation to complete the exam. Conclusions:Unsedated colonoscopy is accepted by a significant proportion of patients. Even when colonoscopy is performed by trainees, the majority of pts (excluding those w/IBS) complete the exam w/acceptable satisfaction ratings and significantly shorter recovery times.