Expanded criteria donor (ECD) kidneys are transplantable deceased donor (DD) kidneys for which the average patient, graft survival, and renal function are inferior when compared to standard criteria DD kidneys. Although the term ECD kidneys has been used since the early 1990s to describe kidneys with various characteristics associated with poorer outcomes, the concept has been formally implemented in U.S. organ allocation. A DD kidney is considered to be an ECD organ if the estimated adjusted risk of graft failure is ≥ 70% (RR ≥ 1.70) compared to DD kidneys with standard characteristics of transplant suitability. The donor characteristics that define an ECD kidney include age ≥ 60 years, or age 50–59 years plus two of the following: cerebrovascular accident as the cause of death, preexisting hypertension, or terminal serum creatinine greater than 1.5 mg/dl. In the aggregate, recipients of ECD kidneys have improved survival compared to end-stage renal disease (ESRD) patients on the kidney transplant waiting list. Patient survival is 5% lower at 1 year and 8–12% lower at 3–5 years for ECD kidney recipients. Adjusted graft survival in ECD kidneys is 8% lower at 1 year and 15–20% lower at 3–5 years after transplantation compared to standard criteria donor kidneys. However, patients less than 40 years of age, African Americans, Asians for whom the median waiting time is less than 1350 days receive no survival benefit from ECD kidney transplantation. Informed choice by the potential recipient is a prominent feature of the allocation policy regarding ECD kidneys. Since there are recipient characteristics associated with no survival benefit following ECD transplantation, nephrologists who refer patients for kidney transplantation should be familiar with the combination of donor and recipient factors that are likely to yield detrimental results.