**Abstract**

Renal replacement therapies (RRT) are commonly used in critically ill patients to achieve solute clearance, maintain acid-base status, and remove fluid excess. The last two decades have seen the emergence of large randomized control trials bringing new evidence regarding how RRT should now be managed in the ICU. RRT is considered a vital supportive care and needs to be adequately prescribed and delivered. This chapter first summarizes the basic principles and characteristics of the three major RTT modalities: intermittent hemodialysis (IHD), prolonged intermittent RRT (PIRRT), and continuous RRT (CRRT). Then, the large body of literature regarding indications for initiation (*early* vs *late*), choice of modality (*intermittent* vs *continuous* and *diffusion* vs *convection*), dosing (*intensive* vs *less-intensive*), and anticoagulation alternatives is reviewed to guide clinical decision-making. Recent evidence in the optimal timing of discontinuing RRT is reported. Finally, troubleshooting scenarios frequently seen in clinics and requiring an adapted RRT prescription are also discussed.

**Keywords:** renal replacement therapy, intermittent hemodialysis, hemofiltration, continuous renal replacement therapy, prolonged intermittent renal replacement therapy, intensive care unit
