Veno-venous bypass (VVB) using a patent para-umbilical vein during liver transplantation (LT) has not been reported previously. Here, we report the decompression of the porto-mesenteric compartment via a patent para-umbilical vein in a patient needing a VVB during LT. Pre-transplant CT-scan showed a large patent para-umbilical vein. A femoro-axillary percutaneous VVB was installed prior to abdominal opening to decompress massive collateral veins in the abdominal wall. The para-umbilical vein was stapled and its proximal end was cannulated and connected to the VVB. The severe atrophy of the native liver allowed to place the whole liver graft in the "liver fossa" while maintaining the native liver pulled toward the left side and connected to the VVB. This maneuver maintained splanchnic venous decompression during latero-lateral cavo-caval anastomosis. The "portal" cannula was clamped and removed. The native portal vein was clamped and divided. Standard portal, arterial, and biliary reconstructions were then performed. A patent para-umbilical vein, present in one third of patients with portal hypertension could be used whenever VVB is indicated during LT in this setting.