Background:Obesity is known to be a main risk factor for early menarche. However, the causal relationship between obesity and early menarche remains controversial.

Aim of the work: This study aimed to estimate the mean age at menarche among high-school students in Sohag and to investigate the association between age of menarche and Body Mass Index.

Materials and Methods:A cross-sectional retrospective study was conducted to investigate the relationship of age of menarche with BMI during 2015-2016 among 954 females in the age range from 15 to 17 years in Sohag. The data from this study included   body height (cm) and body weight (kg). The age at menarche was obtained by a questionnaire. The body mass index (BMI) was calculated, and it was categorized as underweight, normal, overweight and obesity.

Results:The mean age at menarche was13.55±1.035 years. The prevalence of obesity and overweight was 4.9%and 19.4%, respectively. Mean age at menarche was significantly lower among obese compared to normal and non significant among other groups

Conclusion: There is an inverse association between age at menarche and obesity