BACKGROUND Hirsutism, defined by the presence of excessive terminal hair in androgen-sensitive areas of the female body, is one of the most common disorders in women during reproductive age. METHODS We conducted a systematic review and critical assessment of the available evidence pertaining to the epidemiology, pathophysiology, diagnosis and management of hirsutism. RESULTS The prevalence of hirsutism is 3c10% in most populations, with the important exception of Far-East Asian women who present hirsutism less frequently. Although usually caused by relatively benign functional conditions, with the polycystic ovary syndrome leading the list of the most frequent etiologies, hirsutism may be the presenting symptom of a life-threatening tumor ...