Background and Aim: Considering the importance of oral health in children, it is important to find factors affecting it. Eating habits, body mass index (BMI), and educational level and socioeconomic status of the parents have been suggested as factors affecting oral health. Two important indices for evaluation of general and oral health of children are the BMI and DMFT/DMFT, respectively. The purpose of this study was to assess the relationship between these two indices in children aged 6-12 years. Materials and Methods: In this descriptive analytical study, 300 children aged 6-12 years were selected among those referred to the Dental Branch of Tehran Islamic Azad University of Medical Science in 2019-2020 by simple random sampling. The BMI and DMFT/DMFT were calculated, and the relationship between them and the effect of influential factors on dental caries score were evaluated. Data were analyzed by the linear regression model at a confidence interval of 95% and 0. 05 level of statistical significance. Results: The study sample consisted of 168 girls and 132 boys. The mean DMFT was 4. 66±, 3. 39 and the mean DMFT was 1. 44±, 1. 57 Only 11. 34% of the children were underweight and 12. 66% were obese,while, 60. 67% had a normal weight. Oral health and nutritional behaviors of children showed that 71. 3% of them brushed their teeth at least once a day and only 22% used dental floss. A correlation was found between BMI and the rate of caries in permanent teeth (P=0. 046). Conclusion: No statistically significant association was observed between DMFT/DMFT and BMI of children aged 6-12 years.