In living donor liver transplantation, the safety of the donor operation is the highest priority. The introduction of the right lobe graft was late because of concerns about donor safety. We investigated donor liver regeneration by the types of resected segments as well as recipients to assess that appropriate regeneration was occurring. Eighty-seven donors were classified into 3 groups: left lateral section donors, left lobe donors, and right lobe donors. Forty-seven adult recipients were classified as either left or right lobe grafted recipients. Volumetry was retrospectively performed at 1 week, 1, 2, 3, and 6 months, and 1 year after the operation. In the right lobe donor group, the remnant liver volume was 45.4%, and it rapidly increased to 68.9% at 1 month and 89.8% at 6 months. At 6 months, the regeneration ratios were almost the same in all donor groups. The recipient liver volume increased rapidly until 2 months, exceeding the standard liver volume, and then gradually decreased to 90% of the standard liver volume. Livers of the right lobe donor group regenerated fastest in the donor groups, and the recipient liver regenerated faster than the donor liver. Analyzing liver regeneration many times with a large number of donors enabled us to understand the normal liver regeneration pattern. Although the donor livers did not reach their initial volume, the donors showed normal liver function at 1 year. The donors have returned to their normal daily activities. Donor hepatectomy, even right hepatectomy, can be safely performed with accurate preoperative volumetry and careful decision-making concerning graft-type selection.