BACKGROUND Organ shortage has resulted in greater emphasis on partial liver transplantation (PLT) as an alternative to whole-organ liver transplantation. METHODS This study was conducted to assess outcomes in PLT and to compare outcomes of deceased donor split-liver transplantation (DD-SLT) and live donor liver transplantation (LDLT) in adults transplanted in the USA using data reported to the United Network for Organ Sharing in the era of Model for End-stage Liver Disease (MELD) scores. RESULTS Between 2002 and 2009, 2272 PLTs were performed in the USA; these represented 5.3% of all liver transplants carried out in the country and included 557 (24.5%) DD-SLT and 1715 LDLT (75.5%) procedures. The most significant differences between the DD-SLT and LDLT groups related to mean MELD scores, which were lower in LDLT recipients (14.5 vs. 20.9; P < 0.001), mean recipient age, which was lower in the LDLT group (50.7 years vs. 52.8 years; P < 0.001), and mean donor age, which was lower in the DD-SLT group (23.0 years vs. 37.3 years; P < 0.001). Allograft survival was comparable between the two groups (P= 0.438), but patient survival after LDLT was better (P= 0.04). In Cox regression analysis, LDLT was associated with better allograft (hazards ratio [HR]= 0.7, 95% confidence interval [CI] 0.630-0.791; P < 0.0001) and patient (HR = 0.6, 95% CI 0.558-0.644; P < 0.0001) survival than DD-SLT. CONCLUSIONS Partial liver transplantation represents a potentially underutilized resource in the USA. Despite the differences in donor and recipient characteristics, LDLT is associated with better allograft and patient survival than DD-SLT. A different allocation system for DD-SLT allografts that takes into consideration cold ischaemia time and recipient MELD score should be considered.