['Few biomarkers exist to monitor chronic kidney disease (CKD). Neutrophil gelatinase-associated lipocalin (NGAL), a member of lipocalin family, has recently been proven useful to quantitate CKD. The aim of the study was to assess whether NGAL could represent a novel, sensitive marker of kidney function in adult patients with CKD and in kidney transplant recipients.', 'We studied possible relations between serum NGAL, creatinine, and estimated glomerular filtration rate (eGFR) in 80 nondiabetic patients with CKD stages 2 to 4; 80 nondiabetic kidney transplant recipients on a calcineurin inhibitor mycophenolate mofetil, or azathioprine as well as prednisone and in healthy volunteers (n = 32, mean age 50 years).', 'Serum NGAL and creatinine values were significantly higher and eGFR significantly lower in kidney allograft recipients and patients with CKD compared with controls. NGAL rose gradually, reaching the higher value in stage 4 CKD. In univariate analysis serum NGAL was related to serum creatinine, hemoglobin, hematocrit, leukocyte count, and eGFR. Predictors of serum NGAL were creatinine and eGFR among patients with CKD. On univariate analysis serum NGAL was related to serum creatinine, urea, hemoglobin, hematocrit, white blood cell count, calcineurin concentration, eGFR, and albumin in kidney transplant recipients. On multiple regression analysis, predictors of NGAL were creatinine, calcineurin concentration, and high-sensitivity C-reactive protein. In healthy volunteers, serum NGAL correlated with age, serum creatinine, eGFR, and leukocyte count.'] Is neutrophil gelatinase-associated lipocalin a new and sensitive marker of kidney function in chronic kidney disease patients and renal allograft recipients?