The aim of this study was to investigate the antioxidant and anti-apoptotic effects of onion (Allium cepa) extracts (ACE) on doxorubicin (DOX)-induced cardiotoxicity. The rats in the ACE-pretreated group were given a daily dose of 1 ml ACE for 14 days. To induce cardiotoxicity, DOX (30 mg kg-1 body weight) was injected intraperitoneally by a single dose and the rats were sacrificed after 48 h. To date, no such studies have been performed on the cardioprotective and anti-apoptotic potential of ACE on DOX-induced cardiotoxicity. Our data indicate a significant reduction in the activity of in situ identification of apoptosis using terminal dUTP nick end-labeling in cardiomyocytes of the DOX-treated group with ACE therapy. The DOX-treated with ACE groups showed a significant decrease in malondialdehyde levels, and increased activities of superoxide dismutase, glutathione and glutathione peroxidase in comparison with the DOX-treated group. Creatine kinase, creatine kinase MB, lactate dehydrogenase activities and cardiac troponin I levels were significantly decreased in the DOX + ACE group in comparison with the DOX group. These biochemical and histological disturbances were effectively attenuated on pretreatment with ACE. The present study showed that ACE may be a suitable cardioprotector against toxic effects of DOX. Copyright (C) 2011 John Wiley & Sons, Ltd.