Women of reproductive age with psychiatric disorders may experience a fluctuating course of illness over the menstrual cycle. Some data suggest an exacerbation of symptoms during the premenstrual and menstrual phases. The usefulness of such reports is limited, however, by the lack of prospective assessments and the small number of patients involved. Additionally, many reports do not specify whether the exacerbations reflect an intensification of the underlying psychiatric disorder or a new onset of symptoms that occur only during certain phases of the menstrual cycle. Because symptomatic intensification has been reported for illnesses including schizophrenia, bipolar disorder, depression, anxiety disorders, bulimia nervosa, and substance abuse, the data bring attention to the importance of assessing the relationship between a female patient's symptomatic exacerbation and the menstrual-cycle phase in which it occurs. We present a review of the literature on the course of psychiatric symptoms across the menstrual cycle and discuss the potential effects of estrogen and progesterone on these symptoms.