The problem of graft size is one of the critical factors limiting the expansion of adult-to-adult living donor liver transplantation (LDLT). We compared the outcome of LDLT recipients who received grafts with a graft-to-recipient weight ratio (GRWR) < 0.8% or a GRWR > or = 0.8%, and we analyzed the risk factors affecting graft survival after small-for-size grafts (SFSGs) were used. Between June 1997 and April 2008, 427 patients underwent LDLT with right lobe grafts at the Department of Surgery of Samsung Medical Center. Recipients were divided into 2 groups: group A with a GRWR < 0.8% (n = 35) and group B with a GRWR > or = 0.8% (n = 392). We retrospectively evaluated the recipient factors, donor factors, and operative factors through the medical records. Small-for-size dysfunction (SFSD) occurred in 2 of 35 patients (5.7%) in group A and in 14 of 392 patients (3.6%) in group B (P = 0.368). Graft survival rates at 1, 3, and 5 years were not different between the 2 groups (87.8%, 83.4%, and 74.1% versus 90.7%, 84.5%, and 79.4%, P = 0.852). However, when we analyzed risk factors within group A, donor age and middle hepatic vein tributary drainage were significant risk factors for graft survival according to univariate analysis (P = 0.042 and P = 0.038, respectively). Donor age was the only significant risk factor for poor graft survival according to multivariate analysis. The graft survival rates of recipients without SFSD tended to be higher than those of recipients with SFSD (85.3% versus 50.0%, P = 0.074). The graft survival rates of recipients with grafts from donors < 44 years old were significantly higher than those of recipients with grafts from donors > or = 44 years old (92.2% versus 53.6%, P = 0.005). In conclusion, an SFSG (GRWR < 0.8%) can be used safely in adult-to-adult right lobe LDLT when a recipient is receiving the graft from a donor younger than 44 years.