Objective To investigate the diagnosis and treatment of congenital choledochal cysts(CCC) in children. MethodsThe manifestation, auxiliary examination, mode of operation and effect of 42 patients with CCC in children from Jan., 1980 to June, 1999 were analyzed retrospectively.Results The patients with the triad of jaundice, an abdominal mass, and pain was 38.1% among the 42 patients. B-ultrasonic diagnosis was made with a correct diagnostic rate of 95.2%. The effective rate of internal drainage was significantly lower than that of resection of the cyst(χ2=19.36, P＜0.001) while the reoperation rate and incidence of carcinoma of internal drainage were higher than those of resection of the cyst(χ2=11.59, P＜0.001 and χ2=4.97, P＜0.05). Conclusion B-ultrasonic diagnosis is recommended as the first examination method. Internal drainage should be abandoned. Resection of the cyst with Roux-Y hepaticojejunostomy is recommended as the treatment of choice on extrahepatic cholangiectasis. Liver transplantation is a reasonable choice to treat the diffuse intrahepatic cholangiectasis.