Diagnosing acute kidney injury (AKI) may be a challenging situation in the daily practice. Generally, only serum creatinine has been used as a biomarker. However, its value does not exactly represent the actual renal function. The non-existence of early and reliable biomarkers delays targeted treatment and can quickly put at stake the renal. Recent discovery of neutrophil gelatinase-associated lipocalin (NGAL) as structural marker heralds an important step in diagnostic of AKI. The early diagnostic of AKI made possible with detection of urinary or plasmatic NGAL allows early appropriate intervention, which is crucial to short and long-term clinical outcome.