Antioxidant capacity and polyphenolic composition of four endemic medicinal plants from the Eastern Anatolia Region of Turkey; Verbascum cheiranthifolium Boiss. var. cheiranthifolium Boiss., Dactylorhiza chuhensis Renz & Taub., Eryngium bornmuelleri Nabelek and Centaurea karduchorum Boiss. were evaluated for the first time. Aqueous plant extracts, representing decoctions traditionally used for medical purposes by the local population, exhibited high total reducing capacities (ferric reducing antioxidant power assay) and oxygen radical scavenging abilities (oxygen radical absorbance capacity assay) comparable to or higher than numerous Chinese and Ayurvedic medicinal plants and commonly used medicinal herbs. Flavonoids and hydroxycinnamic acids were two major phenolic groups present in the extracts. Extracts of leaves and flowers which are predominantly used for medical purposes exhibited the highest antioxidant capacities and polyphenolic content. Beside their application as traditional medicine, leaves and flowers might be utilized as sources of natural antioxidants. Crown Copyright (C) 2012 Published by Elsevier GmbH. All rights reserved.