Choledochal cysts occur most frequently in East Asian children and rarely in Western adults. Over the past two decades, pediatric treatment has been standardized, but relatively little information is available on the management of Western adults with choledochal cysts. Therefore the aims of this analysis were to compare the presentation, management, and late results of Western adults and children with choledochal cysts. Records were reviewed of patients with choledochal cysts at three academic institutions in Wisconsin. Fifty-seven patients were identified, and 51 of these patients (89%) were managed surgically. Thirty-one patients (54%) were adults, and the adults were more likely to be male (29% vs. 4%, P<0.02). Pain (81% vs. 42%, P<0.01) and cholangitis (35% vs. 15%) were more common in adults. Forty-one patients (71%) had type I cysts, but type IVa or V cysts with dilated intrahepatic ducts were more common in adults (39% vs. 15%, P=0.05). Seventeen adults had undergone biliary surgery prior to referral compared to only four children (59% vs. 15%, P<0.01). Preoperative endoscopic or percutaneous stents were employed more commonly in adults (42% vs. 15%, P<0.01). Hospital mortality was 0%, and morbidity was low in both adults and children (25% vs. 8%). An associated biliary malignancy correlated with age (P<0.05): 0 to 30 years (0%), 31 to 50 years (19%), and 51 to 70 years (50%). In addition, adults were more likely to have late problems with cholangitis (19% vs. 4%, P<0.07) and secondary biliary cirrhosis (13% vs. 4%). This analysis suggests that compared to children, Western adults with choledochal cysts are more likely to have (1) type IVA or V cysts, (2) undergone prior surgery, (3) preoperative biliary stents, (4) an associated biliary malignancy, and (5) late hepatobiliary problems. We conclude that surgery in Western adults with choledochal cysts is frequently complicated and should be performed by specialists in complex biliary surgery.