Acute renal failure (ARF) is a complication frequently observed in critically ill patients. This review provides details regarding the epidemiology and overall care of the ARF patient. ARF is defined and classified based on etiology. These classifications are prerenal azotemia, ischemic ARF, and postrenal azotemia. Examples of drug-induced nephrotoxicity are also outlined. Clinical presentation and diagnostic criteria of ARF are differentiated among the major ARF classes, and management strategies are outlined. These management strategies include preventive, supportive, pharmacologic, and nonpharmacologic interventions. Current standards of practice and investigational therapies are also discussed. Pharmacokinetic monitoring and dosing regimen adjustments in ARF patients with and without renal replacement therapy are reviewed. Finally, a prognostic evaluation of ARF in critically ill patients is provided based on current knowledge of the disease state and treatment options.