The surgical risk and stress to 35 donors in living-related liver transplantation with special reference to donor hepatectomy were analyzed. Donor surgery was performed in one of three ways: (1) left lateral segmentectomy without ligation of the middle hepatic vein (MHV) in the remnant liver (group 1, n=21); (2) left lateral segmentectomy with ligation of MHV in the remnant liver (group 2, n=6) ; and (3) left lobectomy with MHV (group 3, n=8). No critical complications were observed in any group. The postoperative transaminase levels in group 2 were significantly higher than those in groups 1 and 3 (P<.01). Although blood loss was covered by autologous blood transfusion in the first six cases, no banked blood was transfused in any of the cases. Surgical duration was significantly longer and blood loss was significantly greater in group 3 than in group 1 (P<.05) Follow-up computed tomography showed atrophic changes in segment IV in groups 1 and 2. No remarkable changes were seen in segments V or VIII in any of the three groups. Regardless of the type of donor hepatectomy, this procedure appears to be safe and no serious complications occurred after surgery to any donor.