Menstrual dysfunction is common in adolescents who are involved in intensive athletic activity or who are limiting their nutritional intake excessively. The mechanism for hypothalamic amenorrhea in athletes and dieters is not yet fully understood. Other causes of menstrual dysfunction due to pregnancy, central lesions, hormone imbalance, or ovarian failure should be excluded in the athlete with amenorrhea. Amenorrheic patients who have sufficient estrogen effect on their endometrium to have withdrawal bleeding following exposure to progestins should be cycled with progestins on a regular basis to prevent endometrial hyperplasia. Estrogen replacement with cyclic progestin should be considered in the hypoestrogenic adolescent with prolonged amenorrhea. The long-term consequences of hypothalamic amenorrhea in adolescents remain to be determined.