Follow-up data on a girl with 3 beta-hydroxysteroid dehydrogenase deficiency at a pubertal bone age are presented. On examination at age 14.7 years (bone age 12 years), there was no spontaneous breast development. On treatment with hydrocortisone and fludrocortisone, most steroids with the exception of increased 17OH-pregnenolone in plasma and delta 5-pregnenetriol and pregnanetriol in urine, were normal. After 1 week off hydrocortisone, plasma 17OH-pregnenolone, DHA and delta5-androstenediol and urinary delta 5-pregnenetriol and pregnanetriol increased markedly, while plasma 17OH-progesterone increased only slightly. On increased hydrocortisone medication, there was no response of plasma estradiol to HMG. This first observation of a pubertal girl with 3 beta-hydroxysteroid dehydrogenase deficiency indicates that in this patient, the defect persists at a pubertal bone age and that it is not limited to the adrenals, but also affects the ovaries. Girls with this type of defect thus require estrogen replacement at a bone age of about 12 years. The large quantities of pregnanetriol in the urine are not due to an incomplete defect or an additional 21-hydroxylase deficiency, but most likely to the peripheral or hepatic conversion of 17OH-pregnenolone or delta 5-pregnenetriol.