In conclusion, it can be said that there are significant variations among antioxidant properties of kefir samples produced from different cow/soy milk mixtures relation to soymilk ratio in kefir milk. The threshold soymilk level for significant antioxidative activities was 50%. Moreover only the reducing activity did not affect by fat content or inoculation type. These two factors were effective mainly on hydrogen peroxide scavenging activity. Soymilk products are recognized as beneficial to health however; improvement of their undesirable sensorial properties by using cow milk can make them good functional food candidates. In addition, fermentation of these milk mixtures with kefir grains or culture can also bring in the probiotic status.