The in vivo antioxidant properties of green tea extract (GTE) were investigated against doxorubicin (DOX) induced cardiotoxicity in rats. In this experiment, 48 Wistar albino rats (200-250 g) were divided into eight groups (n = 6). Control group received normal saline for 30 days. Cardiotoxicity was induced by DOX (20 mg/kg ip.), once on 29th day of study and were treated with GTE (100, 200 and 400 mg/kg, p.o.) for 30 days. Aspartate aminotransferase (AST), creatinine kinase (CK), lactate dehydrogenase (LDH), lipid peroxidation (LPO), cytochrome P450 (CYP), blood glutathione, tissue glutathione, enzymatic and non-enzymatic antioxidants were evaluated along with histopathological studies. DOX treated rats showed a significant increased levels of AST, CK, LDH, LPO and CYP, which were restored by oral administration of GTE at doses 100, 200 and 400 mg/kg for 30 days. Moreover, GTE administration significantly increased the activities of glutathione peroxidase (GPX), glutathione reductase (GR), glutathione s-transferase (GST), superoxide dismutase (SOD) and catalase (CAT), in heart, which were reduced by DOX treatment. In this study, we have found that oral administration of GTE prevented DOX-induced cardiotoxicity by accelerating heart antioxidant defense mechanisms and down regulating the LPO levels to the normal levels.