Background: In view of the safety and effectiveness of butorphanol as a postoperative analgesic, we designed to compare its activity and side effects with those of ketoprofen, when administered intramuscularly. Methods: Ninety four patients, scheduled for elective total abdominal hysterectomy, received either ketoprofen 100 mg (ketoprofen group) or butorphanol 2 mg (butorphanol group) intramuscularly after surgery. For the first six hours after injection of butorphanol or ketoprofen, the patients were asked to reevaluate the intensity of pain, using numeric rating scale (NRS) and pain score. If the pain score was above 2, supplemental ketoprofen was administered IM. Incidence of side effects were also checked. Results: Butorphanol group showed lower NRS and pain score for the first four hours compared to ketoprofen group, but the incidence of drowsiness was higher in butorphanol group. There were no significant difference in the incidence of other side effects such as nausea and dizziness. In both group, there were neither respiratory depression nor pruritus. Conclusions: Butorphanol gave better relief of postoperative pain compared to ketoprofen. Butorphanol might be a useful drug for postoperative analgesia after hysterectomy with minor side effects.