PURPOSE: Multiple segment 5 vein (V5) anastomoses are common and inevitable in living donor liver transplantation (LDLT) using modified right lobe (MRL) graft. Sacrifice of segment 4a vein (V4a) can simplify bench work and avoid graft congestion. But it could be harmful to some donors in previous simulation studies. This study aimed to evaluate donor safety in LDLT using caudal middle hepatic vein trunk preserved right lobe (CMPRL) graft. METHODS: LDLT using MRL grafts were performed on 33 patients (group A) and LDLT using CMPRL grafts were performed on 37 patients (group B). Group B was classified into 2 subgroups by venous drainage pattern of segment 4: V4a dominant drainage group (group B1) and the other group (group B2). Parameters compared between group A donors and group B donors included operation time, bench work time, number and diameter of V5, remnant liver volume and postoperative course. Those were also investigated in group B1 compared with group B2. And, we reviewed postoperative course of the recipients in groups A and B. RESULTS: Operation time and bench work time in group B were significantly shorter. There were no significant differences in most postoperative parameters between groups B1 and B2. As a result of recipient, V5 patency rates after LDLT were significantly higher in group B. CONCLUSION: LDLT using CMPRL graft is a safe procedure for living donors. Donors with any type of V4 could be proper candidates for CMPRL graft if remnant liver volume is greater than 30% with minimal fatty change.