In this study, chemical composition and antioxidant activity of the essential oil and solvent extracts (hexane, dichloromethane, ethyl acetate, methanol and water) obtained from aerial parts of the endemic plant Marrubium parviflorum subsp. oligodon collected from Afyonkarahisar province in Turkey were examined. The antioxidant ability of solvent extracts and essential oil was evaluated using various methods (beta-carotene-linoleic acid, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, and reducing power assays) and the content of total phenolics and flavonoids were determined. In the essential oil, thirty-one compounds were identified by GC/MS analysis. The major components were (Z,Z)-farnesyl acetone (19.28%), caryophyllene oxide (15.85%) and pulegone (7.15%). In all assays, water extract showed the strongest antioxidant properties due to the highest content of total phenolics. The significantly high correlations were observed between the content of total phenolics and DPPH radical (0.894) and reducing power (0.983) assays. Methanol extract was the richest in total flavonoids. The present results support the traditional and possible use of the essential oil and extracts from M. parviflorum subsp. oligodon in food, pharmaceutical, and cosmetic industries.