Fermented milk is considered as a good source of nutrition for many people. One of the most important substances that could be used in the fermentation of milk is kefir grains. Kefir fermented milk is very important in many health conditions such as bacterial infections, high blood pressure and some hepatic conditions. The aim of this study was to determine the antibacterial activity of fermented milk of kefir against certain pathogenic microorganisms such as Salmonella sp., Escherichia coli, Staphylococcus sp. and Candida albicans using agar diffusion method. The effectiveness of fermented milk of kefir has been studied as hepatoprotective against CCl4 inducing liver toxicity and as a protective agent against kidney and spleen damage using laboratory animal models. The results revealed that the fermented milk of kefir had a potent antibacterial activity against many pathogenic microorganisms and it also showed significant high protection in mice against the toxicity of CCl4. In conclusion, kefir milk can be used as an antibacterial supplement and as a protective agent against liver toxicity.