Objective To evaluate the efficacy of oxycodone or hydromorphone combined with propofol for colonoscopy. Methods A total of 150 patients of both sexes, aged 18-64 yr, weighing 45-85 kg, of ASA physical status Ⅰor Ⅱ, undergoing colonoscopy, were randomly divided into 3 groups(n=50)using a random number table: fentanyl combined with propofol group(group F), oxycodone combined with propofol group(group O)and hydromorphone combined with propofol(group H). In F, O and H groups, fentanyl 1 μg/kg, oxycodone 0.1 mg/kg and hydromorphone 0.02 mg/kg were injected over 60 s, respectively, and then propofol 1.5 mg/kg was injected intravenously.After eyelash reflex disappeared, a colonoscope was placed.When body movement occurred during examination, half of the initial dose of propofol was added.The time for induction of anesthesia, operation time, emergence time, recovery time, occurrence of adverse cardiovascular events, nausea and vomiting and respiratory depression, and amount of propofol consumed were recorded. Results There was no significant difference between the three groups in the time for induction of anesthesia, operation time, emergence time, recovery time, adverse cardiovascular events, respiratory depression, and amount of propofol consumed.Compared with group F, the incidence of nausea and vomiting and respiratory depression was significantly decreased, and the degree was reduced in H and O groups.No significant difference was found between group O and group H in the incidence of nausea and vomiting and respiratory depression and the degree. Conclusion Oxycodone or hydromorphone combined with propofol can be safely and effectively used for colonoscopy and the efficacy is better than that of fentanyl combined with propofol. Key words: Oxycodone; Hydromorphone; Propofol; Colonoscopy