Congenital nephrogenic diabetes insipidus is a hereditary and at birth manifested disease, which is characterized by complete or partial insensitivity of the kidney collecting duct to antidiuretic hormone and its analog deoksi-desamino argentine vasopressin. Patients are thus unable to concentrate urine. The disease is caused by a mutation in the gene encoding either the V2-receptor for antidiuretic hormone (AVPR2) or the water channel – aquaporine type 2 (AQP2). Most patients are phenotypicaly similar. Typical are polyuria and polydipsia. The disease is undoubtedly confirmed by defining a mutation in the patient’s AVPR2 or AQP2 gene. Defining of the mutation enables better genetic counseling of the patient and his fam­ily, and swifter intervention in newborn siblings or patient’s children. The basis of the therapy is maintaining the patient sufficiently hydrated. Medications (hydrochlorothiazide, amiloride, indomethacin) in monotherapy or in combination also have an important role in the ther­apy. The prognosis of the disease is good if the patient is sufficiently hydrated and periods of dehydration are avoided. If not, an acute episode of dehydration that is not correctly man­aged can result in death. Repeated periods of dehydration result in late complications of the disease such as mental retardation, mental concentration disturbances, dilatation of the uri­nary tract and calcinations of the brain. With the present knowledge about the disease there should be no more congenital nephrogenic diabetes insipidus patients with late sequels of the disease in our population.