Menstrual abnormalities create great anxiety among the adolescent females and their families.These irregularities may affect physical, psychological and social well-being and may result in work-related problems for females.High BMI is associated with oligomenorrhea, irregular menstrual cycle and menorrhagia and low BMI is associated with amenorrhea and polymenorrhea. The aim of this study was to improve health of adolescent girls through find the relationship between menstrual irregularities and body mass index. This study was a case control study 132 girls (66 girls in the cases group and 66 girls in the control group) were involved in this study .Menstrual history and BMI were measured for each one. Results: Most cases group were overweight (22.7%) , obese (24.2%) . The common menstrual abnormalities among cases group were heavy flow (26.5%) irregular length of cycle(23.5%),long length of cycle (17.4%) (oligomenorrhea) and long days of flow(16.7%) . High BMI (≥95th percentile) are the most significant risk factors of these common abnormalities among adolescent . Conclusion: High BMI (≥95th percentile) are the most significant risk factors of common cycle abnormalities among adolescent .