OBJECT IVE To e stablish the method for simultaneous determination of levetiracetam and carbamazepine concentrations in human plasma. METHODS After plasma samples were precipitated with methanol ，using carbamazepine-D 10 as the internal standard ，the concentrations of levetiracetam and carbamazepine were determined by high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS）. The determination was performed on XBridge BEH C 18 column with methanol-0.1％ formic acid as mobile phase （gradient elution ）at the flow rate of 0.35 mL/min. The column temperature was set at 40℃，and sample size was 2 μL. With electrospray ion source，a multiple reaction monitoring mode was used for positive ion scanning；the detected ion pairs for quantitative analysis were m/z 171.3→126.3（levetiracetam），m/z 237.1→194.1（carbamazepine）， 247.1→204.1（internal standard ）. RESULTS The linear range of the concentrations of levetiracetam and carbamazepine were 0.5-50 and 0.2-20 μg/mL（r＝0.997 3 and 0.998 5），respectively；the lower quantitative limits were 0.5 and 0.2 μg/mL，respectively. RSDs of intra-day and inter-day were all no more than 10.00％. RE of intra-day and inter-day were within ±4.00％；the average extraction recoveries rate were 95.60％-105.00％；the average internal standard correction matrix factors were 98.40％-110.00％； RSDs of stability tests were all not higher than 5.60％. The concentrations of levetiracetam and carbamazepine in the plasma of 22 patients measured by this method were 3.36-40.90 and 3.64-9.93 μg/mL，respectively. CONCLUSIONS The established method for determining the concentration of levetiracetam and carbamazepine in human plasma is f ast，sensitive，accurate and stable ，and can be used for the monitoring of plasma concentration and pharmacokinetic study in epilepsy patients.