Background: Adolescence is a critical stage of growth and development characterized by significant physical, psychological, and hormonal changes. Menstruation is an important physiological process in adolescent girls, but menstrual problems such as dysmenorrhoea, amenorrhoea, oligomenorrhoea, polymenorrhea, and menorrhagia are common during this period. Body Mass Index (BMI) plays an important role in regulating hormonal balance and may influence menstrual health.

Methods: The present study aimed to assess the relationship between menstrual problems and Body Mass Index (BMI) among adolescent girls in selected schools of Tamil Nadu and Odisha. A quantitative research approach with a descriptive correlational design was adopted for the study. The study was conducted among adolescent girls aged 13–18 years studying in selected schools. A sample of 100 adolescent girls was selected using non-probability purposive sampling technique. Data were collected using a structured demographic questionnaire, menstrual history questionnaire, menstrual problem rating scale, and anthropometric measurements for BMI calculation. Content validity of the tool was established by experts in nursing, gynecology, and public health. The reliability of the tool was tested using appropriate statistical methods.

Results: The collected data were analyzed using descriptive and inferential statistics, including mean, standard deviation, percentage, correlation coefficient, and chi-square test. The findings of the study revealed that menstrual problems were common among adolescent girls and there was a significant relationship between BMI and menstrual problems. Underweight and overweight adolescents showed a higher prevalence of menstrual irregularities.