Vitexicarpin (3’, 5-dihydroxy-3, 4’, 6, 7-tetramethoxyflavone), a polymethoxyflavone isolated from ViticisFructus (Vitex rotundifolia Linne fil.), has long been used as an anti-inflammatory herb in traditional Chinesemedicine. It has also been reported that vitexicarpin can inhibit the growth of various cancer cells. However,there is no report elucidating its effect on human prostate carcinoma cells. The aim of the present study was toexamine the apoptotic induction activity of vitexicarpin on PC-3 cells and molecular mechanisms involved. MTTstudies showed that vitexicarpin dose-dependently inhibited growth of PC-3 cells with an IC50~28.8 μM. Hoechst33258 staining further revealed that vitexicarpin induced apoptotic cell death. The effect of vitexicarpin on PC-3cells apoptosis was tested using prodium iodide (PI)/Annexin V-FITC double staining and flow cytometry. Theresults indicated that vitexicarpin induction of apoptotic cell death in PC-3 cells was accompanied by cell cyclearrest in the G2/M phase. Furthermore, our study demonstrated that vitexicarpin induction of PC-3 cell apoptosiswas associated with upregulation of the proapoptotic protein Bax, and downregulation of antiapoptotic proteinBcl-2, release of Cytochrome c from mitochondria and decrease in mitochondrial membrane potential. Ourfindings suggested that vitexicarpin may become a potential leading drug in the therapy of prostate carcinoma.