SummaryWe report five infants in whom antenatal diagnosis of choledochal cyst was established by ultrasonography, and we review the seven previously reported cases. All but one infant had cystic dilatation of the common bile duct (type 1 cysts), and all infants were diagnosed during the second or third trimester. Eight of 12 infants (67%) developed jaundice in the first few days of life, but only 25% had a palpable abdominal mass. Seven of nine infants (78%) demonstrated complete obstruction of the distal common bile duct on intraoperative cholangiography. Liver histology was available for six patients. Five of six had cirrhosis or fibrosis with bile duct proliferation. All of the infants with fibrosis or cirrhosis had distal common bile duct obstruction. Despite liver biopsy findings of extensive fibrosis plus ascites with failure to thrive in one of our patients, all five patients demonstrated clinical and biochemical improvement following surgical excision and porto- or choledochoenterostomy. All were free of symptoms by 6 months of age. Congenital choledochal cyst should be considered in the differential diagnosis of any sonolucent abdominal mass of the fetus. Neonates with distal common bile duct obstruction and fibrosis in association with presumed choledochal cyst should have prompt surgical exploration, intraoperative cholangiography, and close postoperative follow-up. The long-term outcome with prompt surgical correction is excellent.