OBJECTIVE To establish a LC-MS/MS assay for determining the uptake status of jatrorrhizine,palmatine and berberine in Caco-2 cells. METHODS Chromatographic separation was achieved with gradient elution by a Phenomenex luna C18 column. A API 4000 mass spectrometer system coupled with negative electrospray ionization (ESI) was in the MRM mode. The mobile phase. A was acetonitrile consisted of 4 mmol·L-1 ammonium acetate and 0.08% methanoic acid and the mobile phase B. The uptakes of jatrorrhizine,palmatine and berberine in Caco-2 cells at various concentration and P-gp inhibitors were measured. RESULTS The linearities of jatrorrhizine,palmatine and berberine concentration curves were 0.001 5-0.30,0.001 4-0.28 and 0.001 5-0.030 μmol·L-1 respectively. The uptakes of jatrorrhizine,palmatine and berberine in Caco-2 cells showed a passive diffusion in concentration-dependent manner. The uptakes of jatrorrhizine,palmatine and berberine in Caco-2 cells were increased by P-gp inhibitors significantly.CONCLUSION This fast,sensitive and and specific LC-MS/MS assay was applied to determine jatrorrhizine,palmatine and berberine concentrations in Caco-2 cells.Jatrorrhizine,palmatine and berberine showed well uptake in Caco-2 cells,the P-gp inhibitors maybe participate in the uptake. Jatrorrhizine,palmatine and berberine were the substrates of P-gp.