Acute kidney injury (AKI), or acute renal failure, is associated with hospital stays, increased economic costs, and significant mortality, particularly in the context of critically ill patients in the intensive care setting. Numerous factors contribute to the development of AKI, including reductions in renal blood flow, actions of nephrotoxic drugs, cellular injury or death of proximal tubular cells, and the proinflammatory responses of renal cells. Sepsis and septic shock are the dominant causes of AKI due to impairments in the microcirculation. Dysfunction of the microcirculation subsequently causes blood flow disruption and obstruction in the microcirculation, as well as ensuing ischemia. Prompt recognition and treatment of sepsis may decrease the incidence of AKI mortality and its effects on other organ systems.