This protocol is designed to assess both acute and chronic effects of the calcium channel antagonist, nifedipine, on the hypothalamic-pituitary-adrenal axis in patients with congenital adrenal hyperplasia. The multicenter trial is composed of two phases and will involve a double-blind, placebo-controlled parallel design. The goal of Phase I is to examine the ability of nifedipine vs. placebo to decrease adrenocorticotropic hormone (ACTH) levels, as well as to begin to assess the dose-dependency of nifedipine effects. The goal of Phase II is to evaluate the long-term effects of nifedipine; that is, can attenuation of ACTH release by nifedipine permit a decrease in the dosage of glucocorticoid needed to suppress the HPA axis? Such a decrease would, in turn, reduce the deleterious effects of glucocorticoid treatment in CAH.