This study investigated the ability of green, black, and oolong tea to inhibit the growth of Streptococcus mutans in the human mouth. Tea is known to contain various catechins which have been shown to hinder the in vitro growth of bacteria. Streptococcus mutans is a bacterium known to promote the development of dental caries, which is one of the most common bacterial infections in the world. Twenty-two young adults were divided into groups ingesting either green tea, black tea, oolong tea, or hot water for a period of twenty-one days. Saliva samples were taken once weekly throughout the duration of the study and analyzed using Snyder test agar. It was expected that green tea would show the greatest inhibitory effect on the bacteria, followed by oolong and lastly black tea. Final results indicated that while no large difference was found between the different groups, an overall a decline in bacteria levels across the treatments was shown as the study progressed.