A 13-year-old boy was diagnosed as having primary nephrogenic diabetes insipidus, and symptoms developed at 3 years of age. Subsequently he developed bilateral hydronephrosis and a neurogenic bladder. His pedigree could be explored back 5 generations and represented an inheritance as an X-linked recessive transmission factor. He was treated with indomethacin 2 mg/kg/day plus chlorothiazide 500 mg/day and this new treatment showed a markedly decreased urine output and increased urine osmolarity. (Nephrogenic diabetes insipidus, Hydronephrosis, Indomethacin)