The indications for living donor liver transplantation (LDLT) were successfully expanded from pediatric to adult cases last 15 years. During this process, graft type has been shifted from left side liver to right side liver. Although the introduction of right lobe graft can successfully increase the actual graft size in LDLT, problem related to "small-for-size grafts" have gradually come to light. "Small-for-size syndrome", such as poor bile production, delayed synthetic function, prolonged cholestasis, and intractable ascites, leading to septic complications and higher mortality, are neither specific nor inevitable in low-weight liver grafts. Many factors other than actual graft weight contribute to the occurrence of "small-for-size syndrome". In the clinical setting, surgical modification targeting portal hemodynamics and tissue congestion is a key to overcome "small-for-size syndrome". Until now, several therapeutic options were reported, but further elucidation of the pathogenesis in "small-for-size syndrome" will be a solution for improving the outcomes in adult-to-adult LDLT.