Background: In developing countries including Ethiopia, there is an increase in prevalence of dental carries among school children. In urban areas where there is nutrition transition, the risk for emergence of chronic diseases and dental carries is high. There is limited information in prevalence of dental carries among School aged children in Bahir Dar city. Objectives: This study aimed to estimate the prevalence and determinants of dental caries among private primary school children in Bahir Dar city, northwest region, Ethiopia. Methods: Institution based cross sectional study was conducted from April 1, 2017 to May 15, 2017. Multistage sampling technique was carried out to select a total of 706 students. The data were entered using Epi data version 3.1 and analyzed using SPSS statistical software version 20. Bivariable and multivariable logistic analysis were employed. Adjusted Odds ratio with 95%CI was computed to assess the presence and degree of association between dependent and independent variables. Variables with p-value<0.05 were considered statistically significant in this study. Interviewers administered, pretested structured questionnaires’ were used to assess dietary habit, demographic, socio economic and behavioral variables and using pretested and structured Prepared by American dental association oral examination checklist were used for dental caries assessment Results: A total of six hundred one private primary school children aged 6-15 years were participated in this study making response rate of 85%. The prevalence of dental carries among private primary school children was found to be 31.6 %.( CI; 28.01%-36.79%) and the mean of DMFT was 1.32. Age less than 10 years (AOR=1.254, 1.25-2.72), tooth brushing with tooth paste (AOR=0.41, 0.2-0.82) and mothers’ having illiterate (low grade) educational status 0.67(0.58, 0.77) were associated with dental caries. Conclusion and recommendations: Education and awareness on tooth brushed with paste, for illiterate mothers and children’s specially whose age less than ten (10) years and dental visit to the nearby clinic should be given for children’s to prevent and control dental caries. Using all methods of diagnosis of dental caries and assessment of knowledge, attitude and practices of children and their mothers on tooth brushed with tooth paste should be recommended. Keywords: Dental carries, School age, Private School, Bahir Dar