Abstract: A method for determination of meropenem in infant serum by high performance liquid chromatography (HPLC) coupled with disperse liquid-liquid microextraction was established. 50 μL of 50 mg·L^-1 metronidazole (internal standard) solution and 100 μL of acetonitrile were added into 100 μL of infant serum sample from whole blood of the infant treated with moropenem for 24 h after centrifugation, and 10 μL of dichloromethane was added into all the supernatant after vortex and centrifugation. Then supernatant was taken for HPLC analysis after vortex and centrifugation. Welch C₁₈ column was used as the stationary phase, and a mixture of 3-morphine propyl acid buffer (pH 7.0) and acetonitrile at volume ratio of 1:9 was used as the mobile phase for isocratic elution. Working curve was made by matrix matching mixed standard solution series, and internal standard method was used for quantitative analysis. As shown by the results, linear range of meropenem working curve was in the range of 0.25-100 mg·L^-1, with detection limit of 0.06 mg·L^-1. Recovery test was made on blank serum sample at 3 concentration levels by standard addition method, giving results in the range of 98.6%-99.9%, and RSDs (n=6) of the determined values were ranged from 1.2% to 2.0%. This method has been applied for analysis of 15 actual infant serum samples, with detection amounts of meropenem in the range of 19.2-98.9 mg·L^-1.