Objective: To analyze and report the type of relation present between dental caries and body mass index (BMI)-for-age among schoolchildren in Jazan region of Kingdom of Saudi Arabia. Materials and methods:A cross-sectional study with multistaged random sampling technique was designed to recruit the sample of schoolchildren. Caries was examined using the World Health Organization recommended "decayed and filled teeth"/"decayed missing and filled teeth (dft/DMFT)" method. The BMI-for-age was calculated using the value obtained from body weight and height (kg/m 2 ) of each child. The obtained results were plotted on age-and gender-specific percentile curves by the Centers for Disease Control and Prevention and categorized accordingly. Chi-squared test was conducted to analyze the relation between BMI-for-age and dental caries. Logistic regression was performed to judge the predictor variables. The p-value < 0.05 was considered as significant. Results:A total of 360 children were part of this study with equal recruitment from both genders. The mean dft/DMFT value for girls (2.52) was more than that for boys (1.88); and the (p = 0.00) calculated value was statistically significant. Most of the children had normal BMI-for-age (60.6%) and very few were obese (4.7%). Dental caries, fast food, and snacks between meals were significant independent predictor variables for BMI (p < 0.05). Dental caries was a strong predictor, and the analysis showed that children with untreated caries had 81% (odds ratio = 0.19; confidence interval = 0.65, 0.58) higher chance of suffering from low BMI. Relation between Dental Caries and Body Conclusion:To conclude, this is the first study attempted to see the relationship between BMI-for-age and dental caries among schoolchildren in Jazan city of Kingdom of Saudi Arabia. Negative relation between dental caries and BMI should warrant health promoters about dental caries as a reason for low BMI in a subset of children.Clinical significance: High and alarming percentage of untreated dental caries demonstrates the oral health needs among the schoolgoing children in Jazan region. Public health dentists should develop and implement prevention programs so that the oral health issues among schoolchildren are addressed.