Salvia leriifolia Benth. from Lamiaceae family is a plant native to Iran and Afghanistan with significant applications in medical, pharmaceutical and food industries. The aim of current investigation was to evaluate the composition and antioxidant activity of essential oils (EOs) of S. leriifolia growing naturally in Neyshabur and Bajestan (Northeast of Iran). The aerial parts of the plant were subjected to hydro-distillation and the EOs were analyzed with GC/MS. According to the results, 1,8-cineole (20.24%, 26.39 %), α-pinene (15.14%, 14.39 %) and β-pinene (24.33%, 26.01%) were the main constituents of the EOs of the plant populations in Bajestan and Neyshabur, respectively. Antioxidant activity of the EOs was measured by three different methods, 2,2´-diphenyl-1-picrylhydrazyl (DPPH), thiobarbituric acid reactive species (TBARS) and β-carotene bleaching (BCB). The total EO and three standards (α-pinene, β -pinene and 1,8-cineole) displayed a significant antioxidant effect in all assays. Antioxidant activities obtained by means of TBARS and BCB methods were higher than those measured by the DPPH assay. Moreover, BCB was proved to be the most appropriate method for measurement of antioxidant activity. The EOs of the plants grown in Neyshabur showed stronger antioxidant effects in comparison with those grown in Bajestan.