Over the past decade, there has been a marked increase in the number of primary and revision total hip and knee arthroplasties performed in the United States. Acute kidney injury (AKI) is a common complication of these procedures; however, little is known about its epidemiology in the elective arthroplasty population. We conducted a study to determine the incidence, risk factors, and outcomes of AKI after elective joint arthroplasty. Drawing on the Nationwide Inpatient Sample database, we found that the proportion of hospitalizations complicated by AKI increased rapidly from 0.5% in 2002 to 1.8% to 1.9% in 2012. Multivariate analysis revealed that the key risk factors for AKI were chronic kidney disease and the postoperative events of sepsis, acute myocardial infarction, and blood transfusion. Moreover, codiagnosis with chronic kidney disease increased the risk for AKI associated with all 3 postoperative events. After adjusting for confounders, we found an association between AKI and a significantly increased risk for in-hospital mortality and discharge to long-term facilities. AKI serves as an important quality indicator in elective hip and knee surgeries. With elective arthroplasties expected to rise, carefully planned approach to interdisciplinary perioperative care is essential to reduce both the risk and consequences of AKI.