BACKGROUND: This study was proposed to examine the effects of butorphanol on propofol dose requirements and hemodynamic responses during propofol-N2O-O2 anesthesia. In addition, the effects of butorphanol on the recovery time, sedation score and postoperative first analgesic request time were assessed. METHODS: Forty patients were allocated to 2 groups. Twenty patients received butorphanol (20 microgram/kg, group (B) and the others received an equal volume of placebo (group P) 3 minutes before induction with propofol. After induction, anesthesia was maintained with propofol (6 - 10 mg/kg, iv)-N2O (70%)-O2 (30%). Propofol doses for induction and maintenance and hemodynamic responses (blood pressure, heart rate) were checked. After surgery, sedation score, recovery profiles, and postoperative first analgesic request time were assessed. RESULTS: The induction doses of propofol were lower in group B than in group P. Diastolic pressure and heart rate decreased in group B compared to group P after endotracheal intubation and before skin incision. After skin incision, decreased diastolic pressure and heart rate returned to preanesthetic levels in group P, but the decreased level was sustained in group B. There were group differences in sedation score at 5 and 10 minutes after extubation. In group B, recovery was delayed and more time elapsed before the first analgesic request. CONCLUSIONS: Butorphanol co-administered with propofol reduces the induction dose of propofol and delays the first analgesic request time, but there are significant fluctuations in blood pressure and heart rate during endotracheal intubation and skin incision.