OBJECTIVE:To determine the concentration of clindamycin in woman milk by RP-HPLC.METHODS:The concentration of clindamycin(with tinidazole served as internal standard) was determined by liquid-liquid extraction-HPLC.The chromatographic column was Luna C18 and the mobile phase consisted of acetonitrile-tetrahydrofuran-phosphate buffer (pH 5)(30∶1∶70) at a flow rate of 0.8 mL?min-1.The temperature of the column was kept at 40 ℃ and the detection wavelength was set at 205 nm.RESULTS:The linear range of clindamycin was 0.529～10.580 ?g?mL-1(r=0.996 7) with a lowest detectable limit of 0.2 ?g?mL-1.The average methodological recovery rate of clindamycin was 98.84%;both the inter-day RSD and intra-day RSD of clindamycin(at low,medium and high concentrations) were all less than 5%.CONCLUSION:The method is simple,rapid,sensitive,accurate and reproducible,and it is applicable for the determination of clindamycin concentration in woman milk.