Because of the shortage of deceased donor organs, transplant centers accept organs from marginal deceased donors, including older donors. Organ-specific donor risk indices have been developed to predict graft survival with various combinations of donor and recipient characteristics. Here we review the kidney donor risk index (KDRI) and the liver donor risk index (LDRI) and compare and contrast their strengths, limitations, and potential uses. The KDRI has a potential role in developing new kidney allocation algorithms. The LDRI allows a greater appreciation of the importance of donor factors, particularly for hepatitis C virus–positive recipients; as the donor risk index increases, the rates of allograft and patient survival among these recipients decrease disproportionately. The use of livers with high donor risk indices is associated with increased hospital costs that are independent of recipient risk factors, and the transplantation of livers with high donor risk indices into patients with Model for End-Stage Liver Disease scores < 15 is associated with lower allograft survival; the use of the LDRI has limited this practice. Significant regional variations in donor quality, as measured by the LDRI, remain in the United States. We also review other potential indices for liver transplantation, including donor-recipient matching and the retransplant donor risk index. Although substantial progress has been made in developing donor risk indices to objectively assess donor variables that affect transplant outcomes, continued efforts are warranted to improve these indices to enhance organ allocation policies and optimize allograft survival. Liver Transpl 18:395–404, 2012. © 2012 AASLD.