The underdevelopment of the facial skeleton and structure resulted from malnutrition, which may lead to malocclusion. This study aimed to assess nutrition status using the body mass index (BMI) of high school students (both genders) and its effect on the severity of the malocclusion using the Dental Aesthetic Index (DAI). A cross-sectional study was done on 248 students aged between 11 – 15 years (100 girls, 148 boys), using the simple random technique for selection from high school in Al-Karkh 1st district/Baghdad/ Iraq. The oral examination was done under natural daylight through the window using a disposable mask, gloves, dental mirrors, and dental Vernia, Nutritional status was evaluated by means of body mass index. Which was recorded by measuring Height and weight. About 29.97% of the total sample have a severe malocclusion with highly orthodontic treatment need. There were no significant differences between males and females regarding BMI while in DAI, were significant. The healthy students have a high percentage, while the number of obese girls was lower than the number of obese boys. The gender difference of the DAI values was significant. The boys have highly DAI score, and most of them were obsessed. The relation between the malocclusion and BMI was non-significant. The healthy students present in a high percentage and they have normal or minor malocclusion with no or slight treatment need, this refers to the contribution of the malnutrition and poor health status in bad oral health and malocclusion. Therefore the nutritional plans and diet programs should be put to maintain and improve oral health integrity and overcome the limitations.