To present a novel modification of the surgical technique for open excision of type I choledochal cysts. The treatment of choice for choledochal cyst is surgical excision because such cysts are associated with an increased incidence of cancer. The commonly used operative technique provides poor access to the structures posterior to the cyst, principally the portal vein, and poor visibility of the junction of the cyst with the hepatic ducts and the pancreatic duct. The modification reduces these problems. The key operative step involves early transection of the choledochal cyst near its midpoint. This provides improved access to the back of the cyst. Slitting the sides of the cyst allows clear visibility from within the cyst of the union of the hepatic ducts with the cyst, and the entrance of the pancreatic duct, thus protecting them. Excision of type I choledochal cysts using the described method was completed in 11 adult patients between 2003 and 2012. One patient (9%) was found to have a concurrent gallbladder cancer and underwent an R0 resection at the time of choledochal cyst excision. No patients experienced any intraoperative complications. One patient (9%) developed a portal vein thrombosis postoperatively. The described technique is a safe and feasible method for the excision of extrahepatic choledochal cysts, and provides an advantage in allowing the surgeon to visualize the hepatic and pancreatic ducts from within the cyst and thus protect them during cyst excision.