Background and objectives: Although acute kidney injury is common and significantly increases the risk for intensive care unit and hospital mortality, little is known about its true incidence or how it can be prevented. Furthermore, key unanswered questions remain about the optimal diagnosis and treatment of patients with acute kidney injury. An international, consensus-based, prioritized research agenda was sought to guide clinical and translational research in acute kidney injury. Design, setting, participants, & measurements: A three-step modified Delphi process involving 43 participants representing 19 professional societies, organizations, and multiple stakeholder groups ranging from clinical practice to basic science research was conducted. Results: Twenty research questions were generated across six focus groups. Overall, research priorities generated from nephrologists and intensivists were similar and highly correlated. The stakeholder groups included members from 15 countries. Results from adult and pediatric groups showed important differences, as did results from developing compared with developed countries; however the priority rankings from the developed and developing countries were significantly correlated. Top research priorities in acute kidney injury include determining optimal timing of renal replacement therapy and improving the understanding of the epidemiology of acute kidney injury around the world. Conclusions: Research recommendations that are highly consistent across various stakeholder groups and between developed and developing countries have been produced. It is hoped that these recommendations will prove valuable in guiding future clinical and translational research in this area. Copyright © 2008 by the American Society of Nephrology.