In brief Thirty-two professional female ballet dancers were studied by means of a gynecological questionnaire to determine the prevalence of menstrual dysfunction. Thirty-seven percent had a history of amenorrhea (p <.01 compared with controls). Forty-seven percent had a history of menstrual dysfunction manifested by delayed menarche, amenorrhea, or oligomenorrhea (p <.001 compared with controls). Menstrual dysfunction was related to both strenuous physical exercise and diminished body weight, and it was reversible, often disappearing with significant weight gain or intervals of less intense exercise. Thirteen women had pituitary hormone levels measured before and after exercise, and both were within the normal range.