 Acute kidney injury AKI is a common and devastating complication of critical illness. Once AKI is established, treatment is largely supportive and no intervention has been found to restore kidney function or improve overall survival. Renal replacement therapy RRT, usually in the form of hemodialysis, is frequently needed to manage patients with severe AKI. Such patients have an in-hospital mortality that consistently exceeds 50 with delays in RRT initiation implicated as a possible contributor. A recent meta-analysis suggested that earlier initiation of RRT may improve survival, but this is based on data derived overwhelmingly from observational studies. The investigators recently completed a multi-centre randomized controlled pilot trial that confirmed the feasibility of allocating patients to two different strategies of RRT initiation. Patient recruitment and follow-up, as well as patient safety, were successfully demonstrated during the pilot phase of this research program. The optimal timing of RRT initiation is an existing knowledge gap and a clear priority for investigation. 