Background/Aims: The value of neutrophil-gelatinase-associated lipocalin (NGAL), a novel biomarker in the detection of acute renal failure in children after cardiac surgery, has been highlighted in previous studies. The incidence of percutaneous coronary intervention (PCI) increases, which may possibly result in increased incidences of contrast nephropathy, its potentially serious complication. Therefore, the aim of our study was to assess prospectively NGAL in patients undergoing elective PCI in relation to serum creatinine. Methods: NGAL was assessed in the serum and urine using commercially available kits. Results: We measured urinary and serum NGAL before, and 2, 4, 12, 24 and 48 h after PCI. We found a significant rise in serum NGAL 2 and 4 h after PCI, and a rise in urinary NGAL 4 and 12 h after PCI. Before PCI, serum NGAL was significantly associated with serum creatinine, urea, urinary NGAL, hemoglobin, hematocrit, albumin, age and presence of diabetes. In multivariate analysis, serum creatinine was the only predictor of serum NGAL. Serum NGAL 2 h after PCI correlated with serum creatinine, duration of PCI, HbA1c, hematocrit, hemoglobin and urinary NGAL. In multivariate analysis, the only predictors of serum NGAL 2 h after PCI were serum creatinine, time of PCI and HbA1c. Serum NGAL before PCI was significantly higher in diabetics than in non-diabetics. Conclusions: NGAL may represent a sensitive early biomarker of renal impairment after PCI. Serum creatinine, duration of PCI, but not type and amount of contrast agent, and appropriate treatment of diabetes, reflected by HbA1c, predict a rise in serum NGAL and kidney function following PCI.