This study aims to evaluate the antioxidative activities of traditional Mongolian milk product. Anti-oxidant activity is generally used as merkmal for food function. It is known that reactive oxygen causes various life style diseases, for example hypertension, diabetes, obesity, osteoporosis etc. It is thought that antioxidant activity in our body is very important for preventing these diseases. Many dairy products such as aaruul, eezgii, bayslag orginated from different region of mongolia were used in the study. Anti-oxidant activity was measured by using lag time method. The method is not more popular than ORAC (Oxygen Radical Absorption Capacity) methods; however this method is more simple and easy. Briefly myoglobin-working solution was added to assay samples. After that, 2,2’-Azino-di-[3-ethylbenzthiazoline sulphonate (ABTS) solution as substrate for oxidative reaction was added to the mixture. Immediately the absorbance at 600 nm was read every 30 seconds for 15 min. The anti-oxidant activity of the samples was then calculated as the lag time of the curve of absorbance versus reaction time of the samples. Trolox was used as standard anti- oxidant substance. Using the compound, anti-oxidant activity was expressed as Trolox equivalent value. Milk products including of Japanese products have almost same values (6.5-17.99 µM Trolox eq.). Acid based dairy products such as curd (aaruul) and cottage (aarts) have high oxidization potential. Traditional dairy products antioxidant activities are differ depending on their region.