The chemical composition of essential oil from eight ecotypes of Z. clinopodioides sampled from different points of Coruh valley located in Northeastern Turkey was determined and its total phenolic content and antioxidant activities were also evaluated. Seventeen components, representing 88.56-96.83% of the essential oil were identified by GC-MS. Differences between total phenolic content (varied between 43.41 and 55.71 mg GAE/100 g fresh weight base) and antioxidant activity (ranged from 3.60 to 4.20 mg/ml in DPPH assay) for the essential oil obtained from plant material harvest from different ecotypes were observed. The main components of all samples include (+)-pulegone, 1,8-cineole, limonene, menthol, beta-pinene, menthone, piperitenone and piperitone. Z. clinopodioides essential oil, total phenolic content and antioxidant activity affected by ecotype and environment conditions. The present study provides a theoretical basis for the potential application of essential oil from Z. clinopodioides to be used as a natural resource of antioxidant agents in food industry. The results also support the traditional use of Z. clinopodioides in Turkish folk medicine.