This chapter discusses the diagnosis, evaluation and management of acute kidney injury (AKI). It describes special circumstances for diagnosis and management of acute interstitial nephritis, contrast-induced nephropathy and rhabdomyolysis. A careful patient history frequently reveals etiology of renal failure (e.g., medications or recent administration of contrast dye). A careful patient history and appropriate laboratory testing should reveal the cause of AKI. Once AKI is diagnosed, all drugs that cause renal injury should be discontinued. Volume overload due to AKI can lead to pulmonary edema, which may require respiratory support including noninvasive positive-pressure ventilation or intubation. Patients with AKI who suddenly decompensate should be rapidly evaluated for electrolyte imbalances. Hyperkalemia, which can cause cardiac arrhythmias, is the most concerning. AKI resulting in metabolic acidosis can cause hypotension. Temporary treatment includes volume resuscitation and vasopressors. A sodium bicarbonate infusion can be considered while preparing for dialysis.