The protective effect of garlic ( Allium sativum Linn.) on circulatory lipid peroxidation and antioxidants was investigated during 7, 12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis in male Syrian hamsters. Enhanced lipid peroxidation in the circulation of tumour-bearing animals was accompanied by a significant decrease in the levels of ascorbic acid, vitamin E, reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase. Administration of garlic extract significantly decreased lipid peroxidation with simultaneous depletion of antioxidants. We speculate that garlic exerts its protective effects by decreasing circulatory lipid peroxides and enhancing antioxidants.