BACKGROUND: Propofol and alfentanil are frequently combined to provide total intravenous anesthesia (TIVA). The goals of this study were to determine the target plasma concentration (predicted plasma concentration) of propofol required to provide satisfactory anesthesia in the presence of nitrous oxide over a range of alfentanil infusions for analgesia and to determine the dosing rates required to achieve adequate anesthesia. METHODS: Sixty patients undergoing plastic surgery were anesthetized with 50% nitrous oxide, alfentanil (0 [A0 group] or 5ng/kg loading followed by 0.12ng/kg/min [A5 group] or 10ng/kg loading followed by 0.25ng/kg/min [A10 group] or 20ng/kg loading followed by 0.5ng/kg/min [A20 group]) and propofol using a target-controlled infusion (TCI). The mean target concentration and infusion rate of propofol, and induction and recovery time according to changes of the alfentanil regimen were checked. RESULTS: Induction and recovery time were prolonged in the A0 group more than other groups, and recovery time was shortened in the A10 group more than the other three groups (P < 0.05). The infusion rate and mean target concentration of propofol had significant impact among the groups (P < 0.05). Side effects did not differ among the groups. CONCLUSIONS: The optimal target plasma propofol concentrations and infusion rates of alfentanil, both with satisfactory intraoperative anesthetic conditions and speed of recovery, are 3.51, 3.02, 2.35ng/ml and 0.12, 0.25, 0.5ng/kg/min with 5, 10, 20ng/kg loading in plastic surgery patients. We recommand 0.25ng/kg infusion with 10ng/kg loading of alfentanil combined with 3.02ng/ml of target plasma concentration of propofol as the best combination dosage to shorten recovery time.