BACKGROUND:Several studies reported favorable outcomes of small-for-size (SFS) grafts with graft-to-recipient weight ratio (GRWR) <0.8% in living-donor liver transplantation (LDLT). However, their indications should be carefully determined because they must have been indicated for lower-risk cases over larger grafts with 0.8%≤ GRWR. Furthermore, evidence for minimum requirements of GRWR remains inconclusive. We investigated the safety of SFS grafts against larger grafts by adjusting for confounding risk factors, and minimum requirement of graft volume in adult LDLT. METHODS:We enrolled 417 cases of primary adult-to-adult LDLT in our center between 2006 and 2019. The outcomes of small grafts (0.6%≤ GRWR <0.8%, n =113) and large grafts (0.8%≤ GRWR, n =289) were mainly compared using a multivariate analysis and Kaplan-Meier estimates. RESULTS:The multivariate analysis showed that small grafts were not a significant risk factor for overall graft survival (GS). In the Kaplan-Meier analysis, small grafts did not significantly affect overall GS regardless of lobe selection (vs large grafts). However, GRWR <0.6% was associated with poor overall GS. Although there were no significant differences between the two groups, unadjusted Kaplan-Meier curves of small grafts were inferior to those of large grafts in sub-cohorts with ABO incompatibility, and donor age ≥50 years. CONCLUSIONS:Similar outcomes were observed for small and large graft use regardless of lobe selection. 0.6% in GRWR was reasonable as the minimum requirement of graft volume in LDLT. However, small grafts should be indicated carefully for high-risk cases.