Antenatal Bartter syndrome is a rare condition that can present with different clinical features. These features include early onset maternal polyhydramnios, failure to thrive, prematurity and nephrocalcinosis.We are presenting this 20-day-old girl who had an antenatal history of polyhydramnios. She developed persistent non-bilious vomiting that was associated with constipation soon after birth. She presented with failure to thrive and features suggestive of intestinal obstruction. On the initial evaluation, she was noted to have hypokalaemic, hyponatraemic metabolic alkalosis. The initial work-up was done to exclude surgical and renal causes of her presentation, and the diagnosis was confirmed by gene analysis to be type III-classic Bartter syndrome. She was closely monitored for her growth and development with the appropriate salt replacement therapy.