Background: ECC is now recognized as an infectious disease. The present study was conducted to assess Streptococcus mutans in mother-child pairs of children with ECC. Materials & Methods: The present study was conducted on 56 children of age 1-4 years of both genders. Dental plaque samples were collected from both mother and child.Specific primers to detect the presence of Streptococcusmutans c, e, f and k strains were designed, synthesized and validatedon PCR. Results: Out of 56 patients, boys were 36 and girls were 20.S. mutans strains C was maximum present in 32 cases followed by e in 30, f in 29 and k in 21. The difference was significant (P< 0.05).S. Mutans strain c was seen in 30, f in 28, e in 27 and k in 20 children. Conclusion: Authors found similar number of S. Mutans strains in both children and mothers.