OBJECTIVES: To observe the anti-tumor activities of honokiol on human ovarian tumor in vitro and in vivo. STUDY DESIGN: Cells were treated with honokiol, and the effects on proliferation and apoptosis were examined by MTT, DNA ladder, Hoechst staining, and flow cytometry assays. Expression of Bcl-2 members and caspase-3 were assessed. Measurements of tumor volume and microvessel densities (MVDs) were performed. RESULTS: Honokiol significantly inhibited proliferation and induced apoptosis, with alteration of Bcl-2 members and caspase-3. Administration of honokiol to tumor-bearing animals decreased MVD and resulted in inhibition of tumor growth. CONCLUSIONS: Honokiol could induce apoptosis and inhibit angiogenesis in vitro and in vivo, suggesting a novel and attractive therapeutic candidate for ovarian tumor treatment.