Introduction. Dental caries is the most common oral health disease of school-aged children around the world. In this study, we aimed to assess the prevalence and associated factors of dental caries in primary schoolchildren in Yasuj township, Iran. Methods. In this cross-sectional study, a total of 460 children aged 7–12 years were investigated. Dental examination was performed at school according to the World Health Organization criteria. Sociodemographic data were collected using a structured questionnaire, and caries statuses of children’s teeth were recorded through a dental chart. Data were analyzed using summary statistics, chi-square test, and logistic regression model with odds ratio. Results. The prevalence of dental caries in primary, permanent, and whole dentition among children was 75.3%, 41.1%, and 89.8%, respectively. Among all considered factors, the caries presence in primary teeth was inversely (p<0.001) and in permanent teeth was positively (p<0.001) associated with the children’s age. Moreover, the odds of decaying permanent teeth were significantly higher in girls, in rural children, and in children whose fathers were not an employee compared to their counterparts (p=0.04, p<0.001, and p=0.02, respectively). Conclusions. The prevalence of dental caries among the studied primary schoolchildren in mixed dentition was high and associated with their sociodemographic factors. Providing and implementing preventive, therapeutic, and informative programs for controlling dental caries at individual, family, and school levels are necessary for local health policymakers.