Green tea is generally consumed in the World, since the administration of green tea (GT) is implicated in the decrease of onset of diverse diseases in human. Major components are epigallocatechin-3-gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC). Dysfunction of hepatocyte are associated with the development of diverse diseases such as diabetes. Hyperglycemia has been suggested to be a primary factor in the development of diabetes mellitus. Thus, this study examined the effect of green tea extract and its major components (EGCG, EGC) against 25 mM glucose-induced dysfunction of cultured HepG2 cells, Human hepatocyte cell line. In the present study, treatment of 25 mM glucose induced the increase of cell death and lipid peroxide formation in a dose dependent manner. The treatment of green tea extracts (GTE, 10 mg/mL) prevented 25 mM glucose-induced cell death and lipid peroxide formation in HepG2 cells. cells. In addition, the treatment of EGCG and EGC also prevented 25 mM glucose-induced cell death and LPO formation. Moreover, GTE, EGCG, and EGC prevented 25 mM glucose-induced GSH contents. Among them, EGCG is most powerful agents against 25 mM glucose. In conclusion, GT blocked 25 mM glucose-induced dysfunction of hepatocytes.