Objective To investigate the effects of cyclopamine on the proliferation ,apoptosis and the expression of PSAmRNA in prostate cancer LNCaP cells .Methods LNCaP cells were interfered with different concentrations of cyclopamine (1 ,5 ,10 ,15μmol/L) at the different timepoints(24 ,48 ,72 h) .The poliferation inhibition was measured by the MTT assay ;the apoptotic mor-phological changes were observed by the Hoechst33258 staining method ;the apoptosis rate was examined by the flow cytometry ;the effects of PSAmRNA gene expression was detected by the FQ-RT-PCR .Results 5 ,10 ,15μmol/L cyclopamine groups had obvious inhibition effect on the LNCaP cell proliferation ,which had statistically significant difference compared with the control group (P<0 .01) .10 μmol/L group reached IC50 at 48 h ;the apoptosis rates at 24 ,48 ,72 h in the 10 ,15 μmol/L groups were 37 .21% , 57 .38% ,57 .98% and 21 .16% ,71 .31% ,72 .90% respectively ,the difference had statistically significant difference compared with the control group(P<0 .01) .The cellular apoptotic morphological changes were significantly enhanced with the increase of cyclo-pamine concentration and the extension of action time .The expression level PSAmRNA gene exhibited the obvious decreasing trend with the increase of cyclopamine concentration and was significantly decreased compared with the control group (P< 0 .01) .The PSAmRNA gene expression was extremely low in 10 ,15 μmol/L cyclopamine at different time period .Conclusion Cyclopamine significantly inhibits the proliferation of LNCaP cells ,induces apoptosis and obviously down-regulates the PSAmRNA gene expres-sion in LNCaP cells .Certain concentration of cyclopamine may be effective for treating advanced prostate cancer .