T ea has been known long ago by the public because it is often consumed as a beverage daily. In addition to eliminating hunger, water, tea also has good efficacy against the body's health and oral health. Green tea contains several polyphenolic composition is 30%, caffeine (thenin) 4%, 3% sugar and gum, 7% amino acids, minerals 4%, protein 16%, 8% fat, chlorophyll and other pigments 1.5%, starch 0.5%, crude fiber, lignin and others 22%. Of the composition shown that catechins (polyphenolic substances) contained in green tea has an antibacterial that can inhibit the growth of Streptococcus mutans. Extracts of green tea leaves that have been processed also has antibacterial power of 24 types of bacteria isolated from the roots of the teeth and shown to have antibacterial properties against S.. Mutans. There were significant differences in the influence of the concentration of green tea extract with alpha Streptococcus bacteria inhibition zone. The higher concentration of green tea, the greater the antibacterial power. Effect of green tea against the antibacterial activity of bacteria in the mouth and dental caries is obtained based on the resu Its of studies on green tea which contains catechins with a concentration of 1.5 mg / ml solution is to use effective dose as an antibacterial material, inhibition of the formation of glucan which acts as a interbakteri matrix in the formation of plaque. By inhibition of plaque formation is also hindered the process of dental caries.