Epigallocatechin-3-gallate (EGCG) has shown remarkably anti-cancer activity, with its bioactivity being related to reactive conditions, such as pH and metal ions. The present study investigated the degradation of EGCG and its effect on prostate cancer cell in the presence of Cu 2+. EGCG was incubated with prostate cancer cells, LNCaP, pretreated with or without Cu 2+ . EGCG in F-12 medium was quantified using HPLC and the viability of cells was assessed by gel electrophoresis, flow cytometry, and electron microscope. The results of HPLC showed that EGCG degraded completely within 12 h in F-12 medium with or without Cu 2+. Gel electrophoresis and flow cytometry did not detect apoptosis of LNCaP cells when they were incubated with EGCG. Electron microscopy examination revealed that EGCG-Cu 2+ complex led to damage of cytoplasm membrane in LNCaP cells. It was speculated that not EGCG, but its oxide and complex with Cu 2+ , are the bioactive components responsible for its cytotoxicity to LNCaP prostate cancer cells.