The definition of adolescence emphasizes its sexual nature; it begins with the first physical evidence of sexual maturation and ends with the complete development of primary and secondary sexual characteristics. It is important for all physicians to understand this rapidly changing period during which unique developmental tasks are accomplished. With the experimental and observational elucidation of the dynamics of emotional conflicts that produce physical change, there is no reason for the ethical gynecologist to be ignorant in this area. As illustrated by three clinical examples, secondary amenorrhea can be a defense mechanism on which a struggling adolescent depends for a hold on sanity. The gynecologist must recognize this type of amenorrhea and help the girl by examination, studies, and explanations. If he does not, parents may send her to a gynecologist more willing to comply with their wishes for her to start menstruation.