Introduction: The high prevalence of underweight among children is a serious health concern in Bangladesh. Nutritional status influences students' academic performance directly or indirectly. This study aimed to determine factors that affect the academic performance of students in primary schools. Methods: Data were collected from several schools and madrasahs in Chapainawabganj district, Bangladesh using multistage stratified sampling with proportional allocation technique. Results: The prevalence of underweight children was 32.3%, with 43.0% of them being girls and 21.4% boys. Multiple logistic regression analysis demonstrated that normal weight children were more likely (p