Periodontitis is a periodontal tissue inflammation characterized by migration of the junctional epithelium to the apical, loss of bone attachment and alveolar bone resorption. One of the pathogenic bacteria that causes periodontitis is Porphyromonas gingivalis. One of potentially plant on blocking or killing Porphyromonas gingivalis bacteria is green tea with its active compund on its leaves called katekin. The goal of the research is intended to test the difference effectiveness of anti bacteria capacity of the green tea extract (camellia sinensis) to the growth of Porphyromonas gingivalis bacteria The using of maseri method in getting the green tea extract by using etanol.The using of diffusion method for testing the anti bacteria activity with the concentration of 100%, 70%, 50%, 40%, 30%. The test results showed that extract of Camellia sininesis has MIC against Streptococcus viridans each at a concentration of 100%, 70%, 50% 40%, and 30%. There is an effectiveness difference of green tea extract antibacteria capacity to the growth of Porphyromonas gingivalis bacteria used to block the growth of bacteria and the green tea extract with the most effective antibacteria capacity of 100% concentration.