Objectives : Gleditsiae Spina has the effects of expelling toxins, draining pus, invigorating blood and resolving abscesses. Some clinicians apply the herb for patients suffering from cancer. However, its anti-cancer activities are not well understood. In the present study, anti-tumor agents from Gleditsiae Spina were purified. Methods : The viability of the PC-3 cell line was determined using MTT assay, and the induction of apoptosis by Gleditsiae Spina extract in PC-3 cells was measured by Annexin-V/propidium iodide double staining assay detected by flow cytometry. TLC and HPLC analysis were used to separate and identify the anti-cancer agents. Results : Treatment of the extract resulted in significant decreased cell viability of PC-3 cells in a dose- and time-dependent manner. Dose-dependent apoptotic cell death was also measured by flow cytometry analysis. The anti-cancer agents were successfully separated and identified by using TLC and HPLC analysis and the most potential agent among them was separated from EtOAC fraction. Conclusions : These results might be applied in developing new drugs from natural resources like Korean traditional medicine, and also support the clinical usefulness of herbal medicine.