Acute kidney injury (AKI) affects 5% of critically ill hospitalized children and is a risk factor for increased morbidity and mortality. The current review focuses on new definitions of acute kidney injury, standardized to reflect the entire spectrum of the disease, as well as on ongoing research to identify early biomarkers of kidney injury. Its also provides an overview of current practice and available therapies, with emphasis on new strategies for the prevention and pharmacological treatment of diarrhea-associated hemolytic uremic syndrome. Furthermore, a decision-making algorithm is presented for the use of renal replacement therapies in critically ill children with AKI.