To assess the concentration-responses relationships of propofol, 16 adult patient,ASA grade Ⅰ-Ⅱ,scheduled for upper abdominal operation, were randomly allocated to undergoing epidural block (group Ⅰ, n = 8)or combined anesthesia (group Ⅱ, n = 8) respectively. After a bolus injection of propofol 2.5mg ?kg, blood pressure (BP), heart rate (HR) and tidal volume (TV) were recorded, and drowsiness,amnesia,cooperation and orientation were evaluated by scorring scales in both groups. The venous samples were taken before and after the administration to measure the propofol plasma concentration by spectrofluorophotometric detector. The results revealed that there were no significant differences in pharmacokinetic parameters between two groups;the plasma concentration of propofol at 2. 5rag. L~(-1) was required for adequate anesthesia,and 1.5 to 1.9rag. L~(-1) for hypnosis,the patients were fully awake at 0.94?0.3mg. L~(-1); BP,HR and TV were significantly depressed at more than 2.0rag. L~(-1), and recovered to baseline at less than 1.5mg. L~(-1). It is suggested that there are good relationships between propofol plasma concentrations and its pharmacodynamic responses.