Menarche is an important event during adolescence. For most girls, it marks completion of puberty and the onset of reproductive capability. Menarche usually occurs when both breast and pubic hair development are at Tanner stage 4. Menstrual problems are common during adolescence due to slow maturation of the hypothalamic-pituitary-ovarian axis and can last 2 to 5 years after menarche. Although most problems are explained by anovulation, other causes must be considered and excluded in a logical and cost-effective manner. Frequently, the bleeding problems observed in adolescence require evaluation and intervention.