Dental caries, next to common cold, is one of the most common disorders. It is a bacterial process which damage hard tooth structures (enamel, dentine and cementum). In order to study the cause of dental caries, this study was carried out to isolate the predominant cariogenic organisms from caries samples. A total of 10 caries samples were collected and from the samples 405 microbials isolates were obtained. Among this, 28 morphologically different colonies were identified and from them, 10 predominant were selected for identification. The biochemical and molecular analysis reveals that two organisms belongs to the genus Enterobacter and two belongs to the genus Bacillus. The organisms such as Enterobacter hormaechei, Enterobacter sp., Micrococcus luteus, Klebsiella pneumoniae, Exiguobacterium sp., Staphylococcus sciuri, Acinetobacter radioresistens, Weissella confusa, Bacillus cereus and Bacillus subtilis were identified as predominant organisms in oral cavity.