The incidence of sepsis and acute kidney injury (AKI) is increasing in critically ill patients and both portend a higher risk of morbidity and death. Sepsis has consistently been shown to be a key contributing factor for the development of AKI. Numerous observational studies have found septic AKI to be highly common among the critically ill. Septic AKI patients are characterized by important differences in baseline demographics, acuity of illness and treatment intensity when compared with non-septic AKI. In particular, these patients are often older, have a higher prevalence of co-morbid illnesses, and are admitted for medical or emergency surgical indications. These patients show greater aberrancy in vital signs, laboratory parameters and need for vasoactive therapy and/or mechanical ventilation. Delays in initiation of appropriate antimicrobial therapy independently predict development of AKI in septic patients. Both delays to appropriate antimicrobials and initiation of renal support are also associated with higher mortality. Survival to ICU and/or hospital discharge for septic AKI patients is significantly lower when compared to patients with either non-septic AKI or sepsis alone. However, survivors of septic AKI show trends for greater rates of renal recovery and dialysis independence compared with non-septic AKI. The burden of septic AKI continues to increase and remains associated with an unacceptably high attributable morbidity and mortality. Accordingly, there is continued need to understand its epidemiology, not only to guide in management of these patients at the bedside, but also to stimulate advances in understanding its pathophysiology and in therapeutic interventions to potentially mitigate prognosis.