Congenital cystic dilatation of the common bile duct is an uncommon lesion but one which may be recognized clinically. The diagnosis may be made preoperatively with relative ease if the possibility is considered, since the symptoms and findings are usually fairly clear-cut. The rarity of the lesion is indicated by a calculation from published data.<sup>1,5,8</sup>It would appear that a congenital choledochal cyst will be found approximately once in 200,000 general hospital admissions. The five cases being reported indicate an incidence of 6 per 100,000 general hospital admissions. Approximately 250 cases have been reported to date. It is the purpose of this paper to present five cases of congenital choledochal cyst and to discuss diagnostic procedures, as well as various methods of therapy. The etiology and pathology of this unusual lesion have been adequately discussed in many reviews of the subject.<sup>3,7</sup>It need only be pointed out that