The changes in hormonal milieu associated with menarche, pregnancy, lactation, and menopause are frequently accompanied by changes in the patterns and frequency of migraine. Migraine headache is more common in females and, for many women, the onset of this condition occurs at menarche. As many as 60% of women migraineurs report an association between migraine and menstruation, and evidence suggests that estrogen withdrawal may be a trigger for menstrual migraine in susceptible women. Moreover, in the majority of women, migraine frequency increases during the pill-free interval with oral contraceptive use and during the postpartum period, which are other times of decreasing estrogen levels. Migraine frequency tends to decrease during periods of increasing or stable estrogen levels. For these reasons, the numerous neuroendocrine effects elicited by estrogen have been evaluated to explain its role in migraine. Overall, estrogen appears to be a key factor in menstrual migraine, but it is likely to be only one of several factors that act in concert to trigger migraine in susceptible women. Understanding the relationship of the different hormonal milieus through the natural course of women's lives can guide diagnosis and treatment.