We considered performing living donor liver transplantation (LDLT) in a larger-size recipient. When the recipient was large-sized, or when the donor liver was severely steatotic or had a right-to-left volume discrepancy. We devised dual living donor liver transplantation (DLDLT) to make up for graft size insufficiency and to secure the donor's safety. However, portal vein thrombosis (PVT) presented a challenge for DLDLT because of the need for intact right and left portal veins for the implantation of both liver grafts. Our 52-year-old male patient with hepatitis B cirrhosis had suffered from repeated esophageal and gastric variceal bleeding and underwent 2 trials of a transjugular intrahepatic portosystemic shunt (TIPS). He developed TIPS occlusion and PVT involving the area just above the spleno-mesenteric confluence to the right and left PV. Also, the right PV orifice was destructed and difficult to isolate because of severe periportal inflammation and neointima growth in the TIPS mesh. The patient's two sons were inadequate for donation because of right-to-left volume discrepancy. Therefore, DLDLT using 2 left lobes was necessary to compensate for graft-size insufficiency and to secure donor safety, and we substituted an intact umbilical portion of recipient's left PV for the destroyed right PV. The patient recovered well, and liver function has been normal for more than a year. In conclusion, the umbilical portion of recipient's left PV can be a useful vascular substitute for the reconstruction of a thrombosed main portal branch in DLDLT.