BACKGROUND: Compared with conventional routes of delivering potent analgesics to postoperative patients, transdermal administration of fentanyl offers the advantages of simplicity and noninvasiveness. The analgesic efficacy and safty of transdermal fentanyl patch (TDFP) were evaluated postoperatively. METHOD: TDFP releasing 25 mcg/hr (Group 1) or placebo (Group 2) were applied to 40 women 6 hours before total abdominal hysterectomy under the general anesthesia. Postoperatively, self-administered intravenous fentanyl was maintained with a 20-mcg incremental dose and a 10-min. locking interval. Each group was assessed following 48 hours with respects to vital signs, VAS pain scores, hourly-used fentanyl doses, satisfaction scores and side effects. RESULT: VAS observed 24 hours, 36 hours after operation were significantly lower in group 1 than group 2. Hourly-used fentanyl doses were significantly lower in group 1 than group 2 at 2 hours, 6 hours, 12 hours and 24 hours after operation. The incidence of side effects were similar between group 1 and group 2. CONCLUSION: TDFP-25 mcg applied 6 hours before operation provides supplementary analges-ia after the postoperative period without significant side effects such as respiratory depression.