Congenital adrenal hyperplasia (CAH) with 11-β-hydroxylase deficiency accounts for a small percentage of the overall incidence of this disease in the population. The described case of two sisters touches on the therapeutic problems encountered during the treatment of this rare condition. The authors present the problem of selecting appropriate substitutive doses of glucocorticosteroids that will ensure good control of blood pressure and protect against the development of organ complications caused by hypertension and maintain hirsutism at an acceptable level, with as few complications of the applied treatment as possible. The article emphasizes the role of patient–physician cooperation, which is essential to achieve the therapeutic goals.