Acute kidney injury (AKI) is a clinical condition characterized by acute decline in renal function, with manifestations ranging from minimal elevation of serum creatinine concentration to anuric renal failure. Keeping in view that acquisition of knowledge and research in this important area requires multi-disciplinary collaboration, a group representing members of the Acute Dialysis Quality Initiative and nephrology and critical care societies has established the Acute Kidney Injury Network (AKIN). The First Consensus Conference of this network focused on defining diagnostic and staging criteria for AKI. Changes in serum creatinine levels and urine output were used to define and stage three levels of renal dysfunction. These criteria require evaluation and validation in prospective clinical studies and, perhaps, modifications as more sensitive markers of kidney injury are identified. Other issues that need to be examined include global epidemiology and outcome of AKI and development of strategies to improve outcomes. The vital role of multi-disciplinary conferences for disseminating knowledge and clarifying issues in clinical practice was recognized.