Small changes in kidney function in hospitalized patients are important and associated with significant changes in shortand long-term outcomes. The shift of terminology from ATN and ARF to AKI has been well received by the research and clinical communities. RIFLE/AKIN criteria provide a uniform definition of AKI, and have become the standard for diagnostic criteria. AKI severity grades represent patient groups with increasing severity of illness as illustrated by an increasing proportion of patients treated with RRT, and increasing mortality. Thus, AKI as defined by the RIFLE criteria is now recognized as an important syndrome, alongside other syndromes such as acute coronary syndrome, acute lung injury, and severe sepsis and septic shock. The RIFLE/AKIN classification for AKI is quite analogous to the Kidney Disease Outcomes Quality Initiative (KDOQI) for CKD staging, which is well known to correlate disease severity with cardiovascular complications and other morbidities.39 As CKD stages have been linked to specific treatment recommendations, which have proved extremely useful in managing this disease,39 we have developed recommendations for evaluation and management of patients with AKI using this stage-based approach.