Congenital hypothyroidism is one of the most urgent diseases of the neonate. When diagnosed and treated at an early stage, its most important complication, mental retardation, is preventable. The signs of congenital hypothyroidism are nonspecific in neonates. Only 5% of the cases have characteristic clinical findings. One of the most important and earliest signs is prolonged jaundice during the neonatal period. We report herein a case of congenital hypothyroidism, who presented with icterus accompanied with sludge formation into the gallbladder, which disappeared after treatment with L-thyroxine.