Background/Aims: Contrast-induced nephropathy (CIN) is at present the third leading cause of hospital-acquired acute kidney injury (AKI). Traditionally, it is diagnosed by measuring the increase of the serum creatinine concentration. However, in patients with acute changes in their glomerular filtration rate, serum creatinine is an insensitive marker. This clinical study was designed to investigate whether human urinary interleukin-18 (IL-18) and neutrophil gelatinase-associated lipocalin (NGAL) are early predictive markers for AKI after coronary angiography and their correlation with later cardiac events. Methods: Patients undergoing coronary angiography using low-osmolar contrast medium were enrolled and then followed up for at least 17 months. Urine samples were collected before and 24 h after coronary angiography and IL-18 and NGAL levels measured by using an ELISA kit. Results: CIN was diagnosed in 13 of 150 (8.7%) patients (CIN group); 27 patients without CIN served as control group. At 24 h after the procedure, the urinary IL-18 and NGAL levels were significantly increased in the CIN group, but not in the control group (p < 0.05). The predictable time of AKI onset determined by IL-18 was 24 h earlier than determined by serum creatinine (p < 0.01). Receiver operating characteristic curve analysis showed that both IL-18 and NGAL showed a good performance in early diagnosis of CIN as compared with serum creatinine (p < 0.05). We also found that IL-18 is an independent predictive marker for later major cardiac events: relative risk = 2.09 (p < 0.01). Conclusions: We conclude that urinary IL-18 or NGAL could be early biomarkers of CIN and that urinary IL-18 is well associated with the later cardiac outcomes in patients after coronary angiography.