Failure to thrive in an infant has multiple etiologies and at times, is only manifestation of underlying serious disease. Bartter syndrome is a rare disease that manifests as failure to thrive. It can be diagnosed by a careful history, physical examination, and abnormal electrolyte pattern. It can be alleviated by appropriate management, whereas failure to recognize early can be life threatening. A case of severe failure to thrive in an infant due to neonatal form of Bartter syndrome, its manifestations, management, and outcome is presented in this article.