Androgen receptors are present in numerous tissues throughout the female body, and knowledge of the specific actions of androgens at different sites is increasing, along with the understanding of their contribution to various pathophysiological states. This article reviews the physiology of androgens (testosterone and dihydrotestosterone) and immediate androgen precursors (dehydroepiandrosterone [DHEA], dehydroepiandrosterone sulfate [DHEAS], and androstenedione), with specific reference to the androgen receptor, production and metabolism of C- (19) steroids, circulating androgen concentrations, and androgen actions. In addition, the evidence for physiological modulation of androgens including circadian variation, cyclical variation, age, and natural menopause is reviewed.