Renal replacement therapy (RRT) in the pediatric intensive care unit encompasses a wide spectrum of dialysis modalities, including peritoneal dialysis, intermittent hemodialysis, and continuous hemodialysis. The choice RRT modality depends on the clinical setting, access, availability of equipment, and experience of the staff. Advances in newer access, dialysis equipment, and improved understanding of delivered dialysis have had a positive impact on survival in children with acute renal failure. Renal replacement therapy can also be used in children with specific clinical disease processes such as inborn errors of metabolism. Currently, there is no superior mode of RRT in acute renal failure. There are limited data available on the appropriate choice of modality for the specific disease state. This area requires further prospective studies to define the role of RRT in the pediatric intensive care unit.