Streptococcus mutans is an etiological agent for worldwide distribution of Tooth decay and it is a costly disease compare than other diseases. Evidences on S.mutans as a Multidrug resistant species arose in each country by vast research investigation reports on tooth decay disease. This present investigation was conducted for determining growth optimization parameters of Streptococcus mutans. Fifty decayed samples were collected in dental clinics and dental hospitals around Tirupur, Tamilnadu. Only five isolates were selected for this growth optimization assay. Growth parameters were effects of pH, Temperature, NaCl and Nitrogen sources on S.mutans. In conclusion, growth of the S.mutans isolates exhibited the tolerance at different concentrations of all parameters.