Kasai portoenterostomy is still the first-line surgical treatment of biliary atresia (BA), and the maintenance of good QOL of native liver survivors is a very important issue in the era of liver transplantation. Currently we employ long Roux-en Y portoenterostomy with an antireflux intestinal spur valve as the standard procedure. Technical points of this procedure are described herein. With a small laparotomy, the diagnosis and the type of obstruction are confirmed by direct cholangiography. Dissecting the extrahepatic biliary remnant, the branches of the hepatic artery are identified. The fibrous common bile duct is also dissected and divided close to the duodenum. Small branches of the portal vein toward the caudal lobe through the fibrous remnant are carefully ligated and divided. The fibrous remnant is vertically divided in the middle using an electric cautery. The right and the left parts of the remnant are removed independently, paying careful attention so as not to injure the underlying liver capsule. The long Roux-en Y limb with the antireflux intestinal spur valve is prepared. The hepatic portoenterostomy is performed in the end-to-back fashion. Special care is taken during placing the lateral stitches close to the cut surfaces of the fibrous remnant so as not to involve the cut surfaces into the stitches.