ObjectiveTo establish an accurate and sensitive high performance liquid chromatography-mass spectrometric (HPLC/MS/MS) method for determination of vorinostat (SHA) and M2 metabolites in human serum, which was applicable for pharmacokinetic study of SHA. MethodsThe essay was conducted with an API 3000 HPLC-MS/MS system consisted of a Gemini C18 column (50 mm×3 mm, 3 μm), and the mobile phase consisted of methanol-acetonitrile-water-1 mol/L NH3-formic acid (25:15:60:0.1:0.05) at a flow rate of 0.23 mL/min. Acidulated serum samples were extracted by 3.5 mL diethyl ether which contains 3% isopropyl alcohol and was operated under the multiple reaction monitoring mode using the electrospray ionization technique. d5-SHA was used as the internal standard. ResultsThe retention time of SHA, M2 metabolite and internal standard were 4.1, 3.1 and 4.0 minutes, respectively. The linear range of SHA and M2 metabolite were in the range of 1-1 000 and 2-2 000 ng/mL, and the limit of quantity were 1.0 and 2.0 ng/mL; the method recovery were 93.0%-99.3% and 88.11%-104.12%, respectively. Matrixes effect of SHA and M2 metabolite were blow 9.0%. ConclusionThis method for the quantitative determination of SHA and M2 in human serum was proved to be simple, rapid, sensitive and accurate; it can be applied in the determination of SHA and M2 metabolite.