Population studies on normal and dysfunctional characteristics of menstrual cycles are scarce for western populations and practically non-existent for non-western ones. Recent data suggest that the type of menstrual cycle can be relevant for later gynaecological problems in several ways. The type of menstrual cycle is related to menarcheal age in a way that those with early maturation show more menstrual disorders which are the largest diagnosis category accounting for hysterectomies in adult women. On the other hand menstrual pain is often cited as the main single cause of school absenteeism among adolescent girls. The aim of this study is to describe characteristics of menstrual cycles, prevalence of main dysfunctions and their relationship to the age of maturity. The sample comprises 495 adolescent girls from Marrakech (Morocco) aged 12-19 years. At 13 years, 40% of these girls had reached menarche. The median age at menarche is 13.04. The prevalences of abdominal pain, premenstrual symptoms and irregularity are 69.60, 51.20 and 23.03 respectively. Abdominal pain is significantly more frequent in girls with early menarche