Background/Aims. Different serum and urinary biomarkers have been recently proposed to serve as markers of acute kidney injury. We tested the hypothesis whether NGAL and other biomarkers could represent an early biomarker of contrast nephropathy (CIN) in diabetic patients with normal serum creatinine undergoing cardiac catheterization in comparison with non-diabetic patients. Methods. Serum, urinary NGAL, cystatin C, urinary kidney injury molecule-1 (KIM-1), interleukin-18 (IL-18), and liver-type fatty acid binding protein (L-FABP) were evaluated before and 2, 4, 8, 24, and 48 hours after cardiac catheterization using commercially available kits. Results. In both groups we found a significant rise in serum NGAL after 2, 4, and 8 hours, and in urinary NGAL and IL-18 after 4, 8, and 24 hours after cardiac catheterization. Serum cystatin C increased significantly 8 hours, reaching peak 24 hours after cardiac catheterization in both groups, and then decreased after 48 hours. L-FABP and KIM-1 increase significantly after 24 and 48 hours after cardiac catheterization. Conclusions. CIN was similarly prevalent in both diabetic and non-diabetic patients undergoing cardiac catheterization. NGAL seems to be a potential early marker for nephrotoxicity and predictor of contrast nephropathy. It is particularly important in the upcoming setting of short-time hospitalizations for cardiac catheterization.