Background and objectives: The prescription and delivery of renal replacement therapy for acute kidney injury is subject to a wide variation and is conditioned by a multiplicity of factors. A variety of renal replacement therapy modalities are now available to treat acute kidney injury; however, there are no standards for the dosage, choice of modality, and intensity and duration of these therapies. Although several observational and interventional studies have addressed these topics, there are no consensus recommendations in this field. Design, setting, participants, & measurements: The available literature on this topic and draft consensus recommendations for research studies in this area were developed using a modified Delphi approach and an international multidisciplinary network. Results: The following questions were most important: What is the "dosage" of renal replacement therapy delivered to patients with stage 3 acute kidney injury? What is the optimal "dosage" of renal replacement therapy to maximize patient and renal survival? Is there a minimal "dosage" of renal replacement therapy required in patients with single-organ failure? Does modality of renal replacement therapy selected have an effect on patient and/or renal survival? In cases of continuous renal replacement therapy, does citrate anticoagulation confer a benefit? Conclusions: This report summarizes the available evidence and elaborates on the key questions and the methods that should be used so that the goal of standardizing the care of patients with acute kidney injury and improving outcomes can be achieved. Copyright © 2008 by the American Society of Nephrology.