Abstract: The present study was designed to develop a sensitive and selective high performance liquid chromatography-tandem mass spectrometric method for the determination of Camellianin A in HepG2 cells. The extraction of Camellianin A was achieved using 15% trichloroacetic acid and then separated on a C₁₈ column interfaced with a triple quadrupole tandem mass spectrometer in multiple reaction monitoring mode. The mobile phase was consisted of methanol-water (0.1% formic acid) (55:45, V/V). The total run time was 5.0 min. The method was linear in the concentration range of 0.25-250.0 ng·mL^-1. The lower limit of quantification was 0.25 ng·mL^-1. The intra-and inter-day relative standard deviations of entire concentration range were less than 9.3%. The proposed HPLC-MS/MS method was successfully applied to detect the intracellular concentration of Camellianin A in HepG2 cells.