BACKGROUND: Hepatopancreatoduodenectomy (HPD) is often indicated in the resection of cholangiocarcinoma but is associated with high mortality.1-3 From a risk-benefit perspective, HPD can be justified only when curative resection is achievable.4-6 METHODS: A liver transection-first approach is a surgical technique in which liver transection precedes pancreatoduodenectomy (PD) and skeletonization of the hepatoduodenal ligament in HPD. This approach enables an early assessment of resectability and curability. RESULTS: A 64-year-old with jaundice had a tumor located mainly in the proximal bile duct, spreading from the confluence of hepatic ducts (dominant in the left hepatic duct) to the intrapancreatic bile duct. The right hepatic artery and portal vein existed in close proximity to the tumor. HPD (left hemi-hepatectomy and subtotal stomach-preserving PD) with vascular resection was performed. After liver transection along the Cantlie line, the right Glissonean pedicle was collectively secured inside the liver. The right hepatic artery, right portal vein, and right hepatic duct (RHD) were isolated, and the feasibility of vascular reconstruction was confirmed. After the RHD was divided and the negative margin was confirmed, we proceeded to perform PD. The portal vein was reconstructed between the right portal vein and the portal vein trunk. The right hepatic artery was anastomosed to the second jejunal artery of the jejunal loop with the right gastroepiploic artery as an interposition graft. CONCLUSION: The liver transection-first technique in HPD facilitates early assessment of curability and resectability as well as a safe and secure manipulation and reconstruction of the hepatic artery and portal vein.