Portal vein (PV) size matching between recipient and liver graft is important in preventing anastomotic stenosis in living donor liver transplantation (LDLT). In right liver grafts, the diameter of graft PV is usually >10 mm. Thus, PV size matching does not become critical in adult recipients. If the recipient PV is very large, funneling fence can be attached to graft PV. However, if the diameter of graft PV is <8 mm, it can induce anastomotic stenosis. We experienced a few cases of PV anastomotic stenosis due to small-sized graft PV in >5000 LDLT cases, but graft PV widening was not performed because graft PV is considered as being a no-touch area. In thinking out of the box, we performed wedged-patch venoplasty to exceptionally narrow graft PV. A 4 year-old female patient underwent second LDLT due to progressive deterioration of graft function after 3 years. At first LDLT operation for biliary stresia, an iliac vein conduit was interposed for PV reconstruction. At second LDLT operation, the diameter of interposed PV was 10 mm, but the left liver graft PV was only 6 mm-sized. Uniquely, the left PV was waist only at first-order PV. To resolve this PV waist, a longitudinal incision was made to release the waist. A cold-preserved fresh iliac vein patch was inserted to widen the PV orifice. The patch size was adjusted to match the size of the recipient PV. The patient recovered uneventfully. This wedged-patch venoplasty technique can be applied to small-sized graft PV, to cope with PV size mismatching in LDLT.