The present study was carried out to evaluate the Lipid peroxidation activity and related hypolipidaemic activity of an (EFTO) ethanol fraction of extract of aerial part of Thuja occidentalis Linn. (Cupressaceae). Lipid peroxidation activity was carried out to evaluate the antioxidant potential, and hypolipidaemic activity on cholesterol fed rats. The antioxidant activity of ethanol fraction was increased in a concentration dependent manner. About 100, 150, 200, 250 & 300 μg EFTO (ethanol fraction of extract of aerial part of Thuja occidentalis) inhibited the FeSO4 induced lipid peroxidation in a dose dependent manner and showed IC50 value 195.60μg/ml. in hypolipidaemic activity EFTO at the dose of 200 mg and 400mg/kg body weight significantly reduced serum cholesterol (77 and 92%), LDL (53 and 84%), triglycerides (27 and 46%). The increase in HDL to total cholesterol ratio and reduction in atherogenic index in EFTO treated groups strongly supports anti-atherosclerotic property of Thuja occidentalis. The results obtained in this study indicate that EFTO can be a potential source of natural antioxidant and activities related to this
