Of 218 women with hirsutism 16 (7%) were found to have partial 21-hydroxylase deficiency, while 38 (17%) had partial 3 beta-hydroxysteroid dehydrogenase deficiency. Six women (3%) had a steroid constellation which resembled that of an augmented adrenarche. In the women with enzyme deficiency over-weight and abnormal menstruations were more frequent (50%) than in those without such deficiency (33%). The degree of hirsutism and age at diagnosis were similar in those with and those without partial enzyme deficiency. Furthermore, the diagnosis of partial enzyme deficiency could only be made with certainty by the ACTH stimulation test, because with sole measurement of basal levels (17-hydroxyprogesterone and 21-desoxycortisol in 21-hydroxylase deficiency, and 17-hydroxypregnenolone and dehydroepiandrosterone in 3 beta-hydroxysteroid dehydrogenase deficiency) the enzyme defects are in most instances not revealed.