BACKGROUND: In a gynecologic cone biopsy, fentanyl is commonly used with propofol for its analgesic effect, but it has many side effects, such as bradycardia, respiratory depression and hypotension. A subanesthetic dose of ketamine has an analgesic effect and minimal cardiovascular effects. We wanted to know whether ketamine can be safely used with propofol in a gynecologic cone biopsy instead of fentanyl. METHODS: Forty woman patients were randomly allocated to two groups. All patients were anesthesized with a propofol infusion. Fentanyl 1mug/kg IV was injected 2 minutes before LMA (laryngeal mask airway) insertion in group I, ketamine 0.25 mg/kg IV was injected also in group II. Blood pressure and heart rate were measured before fentanyl or ketamine injection, 1 minute, 3 minutes and 5 minutes after LMA insertion, and during the operation. A numerical rating scale (NRS) for pain and other side effects were checked for 24 hours after the operation. RESULTS: There were no significant differences between the two groups in blood pressure, heart rate, NRS and side effects, but a more stable systolic blood pressure in the ketamine group occured. CONCLUSIONS: For a gynecologic cone biopsy, propofol anesthesia combined with fentanyl or ketamine was not different for stable cardiovascular results, postoperative pain relief and side effects. Therefore, ketamine as an analgesic combined with propofol could replace fentanyl in gynecologic cone biopsy anesthesia.