BACKGROUND: Preemptive analgesia may prevent nociceptive input generated during surgery from sensitizing central neurons and, therefore, may reduce postoperative pain. The purpose of this study is to examine the effect of epidural fentanyl between preincisional (preemptive) and postincisional groups on postoperative morphine requirements. METHODS: Sixty patients (ASA physical status 1 or 2) scheduled for elective total abdominal hysterectomy under general anesthesia were allocated randomly to one of two groups and prospectively studied in a double-blind manner. Group 1 received epidural fentanyl(2 g/kg in 15 ml normal saline) before surgical incision followed by epidural normal saline (15 ml) 15 minutes after skin incision. Group 2 received epidural normal saline(15 ml) before surgical incision followed by epidural fentanyl(2 g/kg in 15 ml normal saline) 15 minutes after skin incision. No additional analgesics were used before or during the operation. Postoperative visual analogue pain scores, PCA morphine requirements and side effects were assessed. RESULTS: Postoperative PCA morphine requirements in preincisional group were significantly less (p<0.05) than those in postincisional group between 6 and 24 hours postoperatively. VAPS was also significantly less (p<0.05) in preemptive group than in postincisional group 12 hours after surgery. CONCLUSIONS: Preemptive analgesia with epidural fentanyl is more effective in reducing the postoperative morphine requirements and VAPS than analgesia with postincisional epidural fentanyl in patients with total abdominal hysterectomy.