Bartter syndrome presenting in neonatal or early infancy is characterized by salt loosing tubulopathy, hypokalemia, and metabolic alkalosis. Failure to thrive is one of the most common findings in neonatal bartter syndrome. Angiotensin converting enzyme inhibitors are one of the therapeutic options for improving growth in these patients.

We describe a case of neonatal bartter syndrome with mild impairment of renal function for whom captopril started to promote better growth but she presented later with clinical and laboratory signs of exacerbation of renal impairment which were significantly resolved after discontinuing captopril.