We present the first report of pregnancy with Cushing's syndrome due to an adrenal cortical adenoma, in which the hypercortisolemia disappeared during the third trimester of pregnancy, but recurred following the delivery of a normal male infant at 38 weeks by Cesarean section. The case is also unique because plasma ACTH levels were elevated during gestation and postpartum. Also, urinary estriol excretion was very low during the third trimester of pregnancy. The relationship of Cushing's syndrome and pregnancy are reviewed. This study points up some of the limitations of the routinely used dynamic tests of pituitary-adrenal function in Cushing's syndrome, and emphasizes the importance of various radiologic procedures in evaluation of patients with Cushing's syndrome.