Abstract<br> Objective: It is known that secondhand smoke exposure is associated with dental caries in children, and it is also speculated that mothers with smoking habits may have little awareness of their dental health and their children. The purpose of this study was to analyze the relationship between smoking habits of mothers and dental health behavior or the oral health condition of their children, and to clarify the factors involved in dental caries of deciduous teeth.<br> Methods: The subjects enrolled in this study were mothers and their children who received health checkup for both 18-month-old children and 3-year-old children in N City, Tokushima Prefecture, Japan. One hundred sixty-five subjects (mothers) were divided into two groups, non-smoker group (n=152) and smoker group (n=13). The results of dental examinations for 3-year-old children and the questionnaire surveys from mothers were collated and analyzed.<br> Results: Dental caries prevalence of deciduous teeth was 46.2% in children of the smoker group, which was significantly higher than that of 21.1% in children of the non-smoker group (p<0.05). Among the questionnaire survey items regarding the regular dental checkup of mothers, the percentage of “no visit“ in the smoker group was 76.9% and 46.1% in the non-smoker group, and it showed a significant difference (p<0.05). In the item of the dental examination for pregnant woman, the percentage of “did not receive” in the smoker group was 76.9% and 43.7% in the non-smoker group, and it showed a significant difference (p<0.05). There were significant differences between the presence and absence of smoking habits of mothers regarding the age of mother (p<0.01) and smoking habits of the other families (p<0.05). In addition, the binomial logistic regression analysis showed that oral hygiene condition (OR=2.92, p<0.05), regular between meal eating (OR=3.99, p<0.01) and smoking habits of mothers (OR=4.13, p<0.05) were significantly corelated with the presence of dental caries in 3-year-old children.<br> Conclusions: These results suggest that the mothers in the smoking group was younger and higher rate that included smoker families, in addition to poor regular dental check-up during pregnancy and currently. It was also suggested that smoking habits of mothers were associated with dental caries in 3-year-old children.