Acute kidney injury (AKI) is a most common and serous complication in hospitalized patients. However, the mortality rate of AKI has not significantly improved during the past few decades. AKI severe enough to require renal replacement therapy (RRT) may be associated with up to 60% hospital mortality. RRT plays a central role in the treatment of critically ill patients with AKI in the absence of fundamental treatment for AKI. Several factors such as the timing of the initiation and discontinuation of RRT for AKI, RRT modality and mode, the delivered dose of RRT, anticoagulants during RRT, type of dialysis membranes, vascular access, dialysate and replacement fluid for RRT have an impact on outcomes in critically ill patients with AKI. Especially in recent years, the optimal timing of the initiation of RRT has been attracted the most attention. Some randomized controlled trials (RCT) and meta-analyses evaluating whether early initiation of RRT for AKI leads to the reduction of mortality were conducted. In this review, we will focus on the current management strategies and problems in RRT for AKI in critical care.