Abstract The chemical composition of the essential oil of the aerial parts of the Ajuga chamaepitys (L.) Schreber ssp. chia (Schreber) Arcangeli collected on Vidlic Mountain (Serbia) from two neighboring localities: normal environmental conditions (NEC) and post fire environmental conditions (PFEC) has been studied by GC and GC/MS. Thirty eight compounds were identified in NEC oil and thirty four in PFEC oil accounted 98.3 % and 98.2 % of the total oil, respectively. The major constituents of NEC and PFEC oil were: Î±-pinene (10.9%, 5.4%), Î²-pinene (22.0%, 14.8%), germacrene D (16.2%, 26.8%), germacrene B (5.9%, 13.6%) and viridiflorol (6.0%, 5.7%), respectively. The antioxidant properties of both oils were evaluated emploing electron transfer antioxidant assays: Folin-Ciocalteu, DPPH and reducing power asaay Fe (III) to Fe(II). Both oil samples had approximately equal and moderate activity in reducing Fe(III) to Fe(II) and Mo(VI) to Mo(V), and weak radical scavenging activity. This is the first report on the content and composition of the essential oil of A. chamaepitys ssp. chia grows in Serbia and also the first report about its antioxidant activity.