We had previously reported on serum neutrophil gelatinase-associated lipocalin (NGAL) as an earlier biomarker of contrast-induced nephropathy (CIN) than serum creatinine (SCr) in 100 patients with chronic kidney disease undergoing coronary angiography.¹ We then compared serum NGAL to serum cystatin C (CysC) in the same group of patients. The SCr, estimated glomerular filtration rate, serum NGAL, and serum CysC were measured at baseline and various time points as appropriate postprocedure. The frequency of CIN was 11% (n = 11). Serum NGAL increased ≥25% from baseline at 24 hours in 7 patients with CIN (P = .04). Serum CysC increased ≥25% from baseline at 24 hours in 4 patients with CIN (P = .008). Changes in serum NGAL and serum CysC from baseline at 24 hours ( values) could diagnose CIN 24 hours earlier than SCr with serum NGAL showing a superior performance.