Follow-up data of a girl with 3β-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 170H-ρregnenolone in plasma and △5-pregnenetriol and pregnanetriol in urine, were normal. After 1 week off hydrocortisone, plasma 170H-pregnenolone, DHA and △5-androstenediol and urinary Δ5-pregnenetriol and pregnanetriol increased markedly, while plasma 170H-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 3β-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 170H-pregnenolone or △5-pregnenetriol.