Objective: Recent research has focused on the use of N-methyl-D-aspartate (NMDA) receptor antagonists for pain management. Several drugs are known to have this action, including ketamine, which exerts its main analgesic effect through NMDA receptor antagonism. This study aimed to evaluate the effect of low-dose ketamine infusion on opioid exposure for patients undergoing myomectomy surgery under general anaesthesia.Methods: A total of 70 women were included in this prospective double-blind trial study. The patients included in this study were American Society of Anaesthesiologists physical status I–II, aged between 18 and 50 years and scheduled for laparotomy myomectomy surgery. Patients were randomised to receive either a bolus of 0.2 mg kg-1 of ketamine followed by a continuous infusion of 0.2 mg kg-1 hr-1 during the operation or a placebo of normal saline. Both groups also received morphine as needed for pain relief. The primary outcome was the total amount of morphine used during the intraoperative and postoperative periods. Intraoperative and postoperative mean blood pressure, heart rate and postoperative visual analogue scale for pain were assessed.Results: Total mean morphine consumption was significantly lower in the ketamine group than in the control group (26±3.5 mg vs. 34.7±3.3 mg, respectively, p<0.05). However, there were no statistical differences between the groups regarding haemodynamics, postoperative pain score and complications.Conclusion: The use of ketamine in low infusion doses intraoperatively during an elective myomectomy procedure produced an opioid-sparing effect by reducing perioperative morphine consumption without significant side effects.