Background: Contrast-induced nephropathy (CIN) is a leading cause of morbidity and mortality in patients undergoing percutaneous coronary intervention (PCI). Chronic total occlusions (CTO) are frequently observed among patients undergoing coronary angiography. Methods: A total of 128 CTO patients were included. Mehran score, lesion characteristics, interventional procedure, serological specimens and devices were recorded. The first group was administered with 1 ml . kg(-1) . h(-1) saline (0.9% NaCl) infusion that started 12 h before the procedure and continued 12 h post procedure as recommended by the guidelines. The second group was administered with saline infusion of 12 ml . kg(-1) . h(-1) only during CTO-PCI procedure, which is called as intensive infusion. Results: CIN development was similar in two groups (four patients in standard hydration group and five patients in intensive hydration group). The amount of saline was significantly higher in the standard group (1,767 +/- 192.2 vs. 1,043.6 +/- 375; p < 0.001). Patients with higher creatinine levels prior to PCI had a higher rate of CIN development after procedure. Interestingly, age, left ventricular ejection fraction, and diabetes mellitus independently predicted CIN. Conclusion: Intensive hydration administration appears to be an effective and cost-effective method in CTO-PCI patients, especially in patients without left ventricular function failure.