Since in the human ovary, estrogens, gestagens and androgens are produced physiologically, disturbed endocrine regulation and function of the cells in the ovary that are capable of steroid synthesis may result in enhanced androgen levels and androgenization. This occurs in conditions which impair the differentiation of the follicular granulosa cells and/or intensity the endocrine activity of the theca folliculi. Furthermore, the ovarian stroma and the hilus cells of the ovary seem to play a role in ovary-related hyperandrogenaemia. The induction of ovarian hyperandrogenic dysfunction is caused by malfunction of the hypothalamus and the pituitary gland. Tumours of the ovary may produce excessive amounts by androgens not found in or very unusual in cases of dysfunctional hyperandrogenaemia, but, far more frequently, hyperandrogenaemia is due to functional and not tumorous disorders.