Aim & Background: Nursing caries (NC) refers to a special type of caries that generally affect 2-4 years old children, showing different prevalence rates in various societies. The goal of this study was to investigate the prevalence rate of this type of caries in the west region of Mazandaran.Methods & Materials: In This descriptive - cross sectional study, 255 children, 2-4 years old, consisting of 127 boys and 128 girls, from nurseries and hygiene houses in Chaloos, Tonekabon and Ramsar cities were investigated. A questionnaire was completed by their mothers carefully about gender, age, order of birth, mother education, the breast - feeding or the bottle feeding. The children were examined by a senior student of dentistry under the natural light by a mirror.Caries, minimally of two maxillary incisors, were also considered as an index. The data were analyzed by SPSS soft ware and submitted to statistical analyses of X2 and Fisher exact tests.Results: The results of this study showed that from among 255 children, age ranging from 2-4 years old, sixty of them (27.5% of the population) was affected with Nursing caries. The prevalence of NC among boys and girls were 33.9% and 21.1%, respectively with a more prevalence among 3-4 years old children than 2-3 years oldones.NC did not show any significant relation with mother's education, order of birth, being breast - fed, milk - feeding before sleep and its duration, but a positive correlation was found between NC and sugary snacks.Conclusion: The prevalence of NC, in the west of Mazandaran, was found 27.5% more than Tehran and Mashhad. There was no significant relationship between NC and breast - feeding.