Background: The combination of propofol Fentanyl for sedation during colonoscopy is characterized by high prevalence of side effects. Etomidate Fentanyl provides fewer hemodynamic and respiratory complications. The aim of our study was to compare the safety and efficacy of propofol Fentanyl and etomidate Fentanyl for conscious sedation in elective colonoscopy.Methods: This double blind clinical trial was conducted on 90 patients aged between 18- 55 years old who were candidates for elective colonoscopy. Patients were randomized to receive sedation with Fentanyl plus propofol or etomidate. Two minutes after injecting 1 micro/kg of Fentanyl, the patients received 0.5mg/kg propofol by infusion (25 m/kg/min) or 0.1 mg/kg etmoidate (15 m/kg/min). Pulse rate, mean arterial blood pressure, respiratory rate, and saturation of peripheral oxygen (SPO2) were monitored. In addition, the patient and colonoscopist satisfaction, the recovery time, sedation and pain score in both groups were assessed.Results: Sedation score in propofol group was higher. Pain score as well as the physician and patient satisfaction showed no significant difference between the two study groups. Hemodynamic changes and arterial saturation were the same in both groups. The duration of recovery was 1.27±0.82 minutes in the etomidate group; versus 2.57±2.46 minutes in the propofol group (P=0.001). Recovery time in the etmoid group was 2.68±3.14 minutes and in the propofol group was 5.53±4.67 minutes (p=0.001).Conclusion: The combination of Fentanyl and etomidate provides an acceptable alternative to sedation with Fentanyl and propofol with the advantage of significantly faster recovery time, in the outpatient setting.