Background and objectivesPediatric patients frequently require deep sedation or general anesthesia for colonoscopy. This study was designed to compare the sedative efficacy of remifentanil–ketamine combination with propofol–ketamine combination in children undergoing colonoscopy. MethodsSeventy patients, between 2 and 16 years of age, scheduled for diagnostic colonoscopy were randomly allocated into two groups. Remifentanil–ketamine group received intravenous ketamine 2mg.kg−1 and remifentanil 0.25μg.kg−1 combination, followed by 0.1μg.kg−1.min−1 remifentanil infusion. Propofol–ketamine group received intravenous propofol 1 and 2mg.kg−1 ketamine combination, followed by 1mg.kg−1.h−1 propofol infusion. In the case of children discomfort (cry, movement, and cough), remifentanil 0.1μg.kg−1 in the remifentanil–ketamine group or propofol 0.5mg.kg−1 in the propofol–ketamine group were administered to improve children discomfort. Despite the therapy given above, if children still experience discomfort, 1mg.kg−1 of ketamine was administered as a rescue drug, regardless of the group. Ramsay sedation score, hemodynamic variables, drug requirements, gastroenterologists’ satisfaction, colonoscopy duration, recovery time, and side effects were recorded throughout the procedure and the recovery period. ResultsThe percentage of patients with a Ramsay sedation score of 4 or higher during the procedure was 73.5 and 37.1% in remifentanil–ketamine and propofol–ketamine groups, respectively (p=0.02). Systolic and diastolic blood pressure variables were significantly higher only after induction in the remifentanil–ketamine group than in the propofol–ketamine group (p=0.015). ConclusionCoadministration of ketamine with either remifentanil or propofol effectively and safely provides sedation and analgesia in children undergoing colonoscopy. Sedation scores were significantly better in remifentanil–ketamine group than in propofol–ketamine group.