Introduction: Nutritional status is a condition of the body which is the result of a balance between food intake and nutritional needs. Good nutritional status is very important for children, but in reality there are still many malnourished children. Lack of nutrition and the habit of consuming excess food can make teeth susceptible to caries. The tooth with the highest caries incidence is mandibular first molar which is the most important tooth in mastication process. The purpose of this research is to determine the relationship between nutritional status and the incidence of caries in permanent mandibular first molar children aged 7 years in Plalangan Village, Jember, East Java, Indonesia. Methods: This is an analytic observational research with a cross-sectional approach. The sampling technique of this research is Total Sampling, which uses the entire population as the sample of this study. This research was conducted by measuring the nutritional status of BMI-for-age based on anthropometric standards from the Minister of Health of the Republic Indonesia No. 2 of 2020 and examining the oral cavity to see whether there is caries or not in the permanent mandibular first molar. Results: The results of the Chi-Square Test showed a value of 0.036. Conclusion: The result shown that thinness and overweight children have a higher caries incidence than normal weight children. There is a significant relationship between nutritional status and incidence of permanent mandibular first molar caries.