BACKGROUND: One of the goals of anesthesia is a complete, comfortable, and rapid recovery without sequelae from anesthesia. Perioperative intravenous fentanyl treatment, due to its rapid onset and brief duration of action, is the one of the most commonly used narcotics. However, the dosage of fentanyl used varies a great deal depending on the purpose and plan of postoperative pain management. When a large dose of fentanyl is used, delayed emergence may occur. This study is designed to evaluate the effective dose of fentanyl and ketorolac for postoperative analgesia. METHODS: Sixty ASA physical status 1 or 2 patients were divided into three groups: fentanyl group (fentanyl 2micro gram/kg, n = 20), mixed group (fentanyl 1micro gram/kg and ketorolac 0.5 mg/kg, n = 20) or ketorolac group (ketolorac 1 mg/kg, n = 20). Each group received a drug ten minutes before the expected termination of the surgical procedure. At the operating room, durations for return of spontaneous breathing, spontaneous eye opening, and extubation were evaluated. At the recovery room, VAS (Visual Analogue Scale) and K-MMSE (Korean Minimental Status Exam) were measured. RESULTS: When compared to the ketolorac group, return times of the spontaneous breathing, spontaneous eye opening, and extubation were prolonged in the fentanyl group (P < 0.05). In the mixed group, the duration of these parameters was intermediate. Postoperative pain scores were also significantly lower in the fentanyl group and mixed group than in the ketorolac group (P < 0.05). The K-MMSE scores for emergence from anesthesia were not significantly different between the three experimental groups. CONCLUSIONS: Based on these results, we suggest that intravenous administration of reduced doses of fentanyl and ketorolac could effectively reduce the pain score without delay from emergence.