© 2019 American Medical Association. All rights reserved. Importance: In light of the growing population of older adults in the United States, older donors (aged ≥70 years) represent an expansion of the donor pool; however, their organs are underused. Liver grafts from older donors were historically associated with poor outcomes and higher discard rates, but clinical protocols, organ allocation, and the donor pool have changed in the past 15 years. Objective: To evaluate trends in demographics, discard rates, and outcomes among older liver donors and transplant recipients of livers from older donors in a large national cohort. Design, Setting, and Participants: Prospective cohort study of 4127 liver grafts from older donors and 3350 liver-only recipients of older donor grafts and 78990 liver grafts from younger donors (aged 18-69 years) and 64907 liver-only recipients of younger donor grafts between January 1, 2003, and December 31, 2016, in the United States. The Scientific Registry of Transplant Recipients, which includes data on all transplant recipients in the United States that are submitted by members of the Organ Procurement and Transplantation Network, was used. Exposures: Year of liver transplant and age of liver donor. Main Outcomes and Measures: Odds of graft discard and posttransplant outcomes of all-cause graft loss and mortality. Results: In this study, 4127 liver grafts from older donors were recovered for liver transplant across the study period (2003-2016); 747 liver grafts from older donors were discarded, and 3350 liver grafts from older donors were used for liver-only recipients. After adjusting for donor characteristics other than age and accounting for Organ Procurement Organization-level variation, liver grafts from older donors were more likely to be discarded compared with liver grafts from younger donors in 2003-2006 (adjusted odds ratio [aOR], 1.97; 95% CI, 1.68-2.31), 2007-2009 (aOR, 2.55; 95% CI, 2.17-3.01), 2010-2013 (aOR, 2.04; 95% CI, 1.68-2.46), and 2013-2016 (aOR, 2.37; 95% CI, 1.96-2.86) (P <.001 for all). Transplants of liver grafts from older donors represented a progressively lower proportion of all adult liver transplants, from 6.0% (n = 258 recipients) in 2003 to 3.2% (n = 211 recipients) in 2016 (P =.001). However, outcomes in recipients of grafts from older donors improved over time, with 40% lower graft loss risk (adjusted hazard ratio, 0.60; 95% CI, 0.53-0.68; P <.001) and 41% lower mortality risk (adjusted hazard ratio, 0.59; 95% CI, 0.52-0.68; P <.001) in 2010 through 2016 vs 2003 through 2009; these results were beyond the general temporal improvements in graft loss (interaction P =.03) and mortality risk (interaction P =.04) among recipients of liver grafts from younger donors. Conclusions and Relevance: These findings show that from 2003 to 2016, liver graft loss and mortality among recipients of liver grafts from older donors improved; however, liver graft discard from older donors remained increased and the number of transplants performed with liver grafts from older donors decreased. Expansion of the donor pool through broader use of liver grafts from older donors might be reasonable..