In order to investigate the inhibitory effect of matrine on the expression of prostate specific antigen (PSA) and androgen receptor (AR) in prostate cancer cell line LNCaP in vitro, LNCaP cells were treated with matrine at different concentrations (0.5, 1.0, 1.5, 2.0 g/L) for 12-36 h. The growth activities of cancer cells were determined by MTT colorimetric assay. The AR level was measured by Western blotting. The expression of PSA was detected by using AXSYM system-chemical luciferase methods. The results showed that matrine could effectively inhibit the growth of androgen-dependent prostate cancer cell line LNCaP in vitro in a time- and dose-dependent manner (P<0.05). It could obviously decrease the level of AR (P<0.01) and inhibit the expression of PSA in a dose-dependent manner (P<0.05) in LNCaP cells. It was concluded that matrine could significantly suppress the growth of LNCaP cells and inhibit the expression of PSA and AR of prostate cancer cells.