Identifying patients at high risk of developing renal dysfunction and poor outcomes remains a challenge in AHF. Coupled with a lack of effective therapeutic options, this poses a problem for clinicians. Biomarkers such as NGAL can be used as diagnostic or prognostic tools, though their application requires careful and thorough evaluation. Despite the extensive but conflicting literature on plasma NGAL, our analyses in this very large group of well-characterized AHF patients, together with findings from AKINESIS, indicate fairly poor accuracy for predicting WRF.