The authors have evaluated the pattern of plasma androgens in females from puberty to old age and in several pathological states. Androgen circulating levels were correlated to the development of the hypothalamus-pituitary-ovary axis during puberty, and analyzed in the different phases of the menstrual cycle in fertile women and during the menopausal period. Androgen plasma levels in patients with hirsutism, polycystic ovary syndrome, and infertility were examined and discussed for their etiopathological role and diagnostic significance.