Introduction: Dental and root caries are one of the disadvantages of removable pastial dentires. A selective population with 30-60 years old living in the mashhad were examined from the point of caries. Materials and Methods: 78 patients which worn 125 removable partial dentures for 3-4 years were examined to determine the relationship among removable partial denture, their design, age, sex, systemic disease, oral hygiene, dental caries and root caries of those patients.Results and Conclusion: The results showed that %70.5 higher prevalence of exposed root surface and %80.9 root caries, particularly on abutment teeth. In addition, root caries lesions on abutment surfaces were found to be larger and more active than those on nonabutment surfaces.