Four cases in adults of a deficiency in the 11 beta-hydroxylation of corticosteroids were investigated by both basal and dynamic biological studies. Symptoms varied from patient to patient; hirsutism, menstrual disturbance, acne, deepening of the voice, and arterial hypertension appeared post puberty. Basal testing demonstrated elevated levels of plasma androgens. These include delta 4-androstenedione (patients, 3.80-6.43 ng/ml; normal, 1.33 +/- 0.33 ng/ml), urinary 17-ketosteroids (patients, 11.8-16.7 mg/24 h; normal, 5-10 mg/24 h), and urinary dehydroepiandrosterone. The basal tests were often insufficient to show the accumulation of the precursors (especially 17-hydroxyprogesterone) which are often given as evidence for an increase in ACTH stimulation. In studying the levels of the mineralocorticoids, there was shown to be an increased basal level of tetrahydrodeoxycorticosterone (patients, 142-317 microgram/24 h; normal, 60-80 microgram/24 h) which was raised by ACTH stimulation. These results, therefore, confirm the characteristic partial enzyme defect and give evidence for the heterogeneity of this syndrome. Based on the above observations, we believe it is appropriate to rename this condition adult adrenocortical 11 beta-hydroxylation defect rather than late-onset congenital adrenal hyperplasia.