A 7-year-old girl had growth retardation, hypertension, and hypokalemic alkalosis. Baseline serum aldosterone concentration and plasma renin activity were low and unresponsive to sodium deprivation and to orthostatic changes. Baseline serum progesterone, 17-hydroxyprogesterone, 11-deoxycortisol, and cortisol levels were normal and adequately responsive to ACTH stimulation. No steroid was found abnormally elevated. A diagnosis of 11 beta-hydroxysteroid dehydrogenase deficiency was established on the basis of elevated urinary tetrahydrocortisol plus allotetrahydrocortisol/tetrahydrocortisone ratio, determined by gas chromatography-mass spectrometry. Evaluation of bone mineral metabolism and parathyroid function, and skeletal radiographs, revealed the presence of rickets and secondary hyperparathyroidism. Treatment with spironolactone alone for 2 months corrected hypertension, hypokalemic alkalosis, and all laboratory and radiologic evidence of rickets and hyperparathyroidism, resulting in acceleration of growth rate. The response to spironolactone suggests that a hypermineralocorticoid state is responsible for the hypertensive syndrome and that rickets and hyperparathyroidism could be a consequence of excess mineralocorticoid activity.