Background: Streptococcus mutans (S. mutans) and Streptococcus sorbinus (S. sorbinus) have been considered to be the most important micro-organisms associated with dental caries. Therefore, purpose of this study is to detect and correlate the presence of S. mutans and S. sobrinus in the dental plaque of caries free and caries active children, by using Polymerase chain reaction (PCR) method. Materials and Methods:Twenty patients aged between ages 4-8 years were included in the study. The subjects were divided in two groups: Group A consisting of ten children with early childhood caries and Group B consisting of ten caries-free children. Dental examinations were performed using a plane dental mirror and explorer. Plaque sample was collected from the cervical margin of the teeth by using explorer. PCR testing was performed for S. mutans and S. sorbinus. The data was analyzed by using SPSS software. The caries score data was analyzed among groups by applying Fischer's exact test. The P value <0.05 was considered as significant.Results: S. mutans was present in all patients, whether they were caries active or caries free. There was no statistically significant difference in the presence of S. sorbinus in caries active patients as compared to caries free patients. It was also noticed that S. sorbinus was found more in male patients as compared to females, the difference being statistically non-significant. Conclusion:Children harbouring both S. mutans and S. sorbinus had a higher incidence of dental caries as compared to the presence of either organism alone.Among the oral bacteria, Mutans streptococci have been implicated as a major cariogenic bacteria. The degree of colonization of these organisms correlates with the prevalence of dental caries in children and experimental animals.Mutans streptococci is divided into seven species: Streptococcus mutans, Streptococcus sobrinus, Streptococcus downei, Streptococcus rattus, Streptococcus cricetus, Streptococcus ferus, and Streptococcus macacae. Among these S. mutans and S. sobrinus are strongly associated with human dental caries [6]. Epidemiological studies have reported that S. mutans is more prevalent than S. sorbinus in the oral cavity, but have also shown that the prevalence of S. sorbinus is more closely associated with a high caries experience [7].Molecular methods for bacterial identification and enumeration now make it more precise to study the microbiota associated with caries. DNA sequence-based assays can be used to identify closely related species that are difficult to differentiate by traditional, culturebased approaches [8]. Various methods have been used for detection, including biochemical tests, immunological tests, DNA probes, and Polymerase Chain Reaction (PCR). Among these, the PCR method is currently being applied to the detection of putative pathogens and the identification of human cariogenic bacteria because it is rapid, sensitive, and simple.The purpose of this study is to detect and correlate the presence of S. mutans and S. sobrinus in...