Choledochal cyst remains a rare pathology in western countries. Over the past 15 years, 18 children were diagnosed with choledochal cyst at Hospital Sainte-Justine. There were 14 girls and 4 boys with an average age of 7.4 years ranging from newborn to 15 years. Abdominal pain, jaundice and abdominal mass were present in 70%, 54% and 7% respectively. Only one patient, a 15 years old girl had all three symptoms. Abdominal ultrasonography was diagnostic in all cases and in two cases, a cystic dilatation was found in the antenatal ultrasonography. Transvesicular cholangiography was performed successfully in 11 patients and showed a detailed anatomy of the biliary tract preoperatively. Sixty-seven percent of the cysts were type I while 33% were type IV. A common channel was found in 43% of the cases. Sixteen patients underwent cyst excision followed by Roux en Y hepatico-jejunostomy, one patient with associated biliary atresia had a porto-enterostomy and one patient had a cysto-duodenostomy. The last patient had recurrent episodes of cholangitis and required reoperation while the others are doing well and free of infection. With the liberal use of ultrasonography, the diagnosis of choledochal cyst is being done earlier improving the long term prognosis. Transvesicular cholangiography is a very useful addition in the preoperative investigation of these patients. Roux en Y hepatico-jejunostomy was associated with minimal morbidity and mortality and gave excellent result.