Disorders of androgen excess are among the most common reproductive endocrine abnormalities in women. Most cases of hyperandrogenism probably result from abnormal regulation of the androgen-forming enzymes in the ovary, adrenal, or both. This may be due to an intrinsic abnormality making the enzyme respond inappropriately to regulatory factors, or it may be secondary to excess or deficiency of endocrine factors such as luteinizing hormone or insulin or of paracrine or autocrine growth factors. Hyperandrogenism is associated with not only infertility and hirsutism but also insulin resistance, diabetes, and heart disease. Thus, its proper diagnosis and management is essential to the maintenance of good health. This review examines the sources, pathophysiology, long-term consequences, and therapy of androgen excess.