Smilax excelsa L. leaves are used widely in the Black Sea region of Turkey for consumption in the daily diet and in folk medicine for their medicinal properties. In the present study, different antioxidant tests were employed in order to evaluate the antioxidant activities of water, infusion, ethanol and ethyl acetate extracts of S. excelsa leaves. In addition, the results were compared with natural and synthetic antioxidants. The levels of total phenolics, total flavonoids and anthocyanins of the extracts were also determined. The extracts were found to have different levels of antioxidant properties in the test models used. All extracts had good total phenolic and flavonoid contents, inhibited lipid peroxidation, showed radical scavenging and iron-chelating activities. Therefore, the leaves of the plant could be considered as a significant natural antioxidant source. (C) 2008 Elsevier Ltd. All rights reserved.