Veno-venous ECMO is increasingly used for the management of refractory ARDS. In this context, acute kidney injury (AKI) is a major and frequent complication, often associated with poor outcome. We aimed to identify characteristics associated with severe renal failure (Kidney Disease Improving Global Outcome (KDIGO) 3) and its impact on 3-month outcome.Between May 2009 and April 2016, 60 adult patients requiring VV-ECMO in our University Hospital were prospectively included.AKI occurrence was frequent (75%; n=45), 51% of patients (n=31) developed KDIGO 3 - predominantly prior to ECMO insertion - and renal replacement therapy was required in 43% (n=26) of cases. KDIGO 3 was associated with a lower mechanical ventilation weaning rate (24% vs 68% for patients with no AKI or other stages of AKI; p0.001) and a higher 90-day mortality rate (72% vs 32%, p=0.002). Multivariate logistic regression suggested that KDIGO 3 occurrence prior to ECMO insertion, as well as PaCO257mmHg and mSOFA12 were independent risks factors for 90-day mortality.KDIGO 3 AKI occurrence is correlated with the severity of patients' clinical condition prior to ECMO insertion and is negatively associated with 90-day survival.