Background: The use of iodinated contrast media can result in nephropathy especially in high risk patients. Whether iodixanol is less nephrotoxic than ioxaglate in high-risk patients is uncertain. Methods: We conducted randomized, prospective, single center study comparing the nephrotoxic effects of an iso-osmolar, dimeric, non ionic, contrast medium (iodixaol), with those of a low-osmolar, ionic, dimeric contrast medium (ioxaglate). This study involved 282 patients with calculated creatinine clearance (by Cockroft-Gault formula) ���60mL/min who underwent coronary angiography. Half-saline was given intravenously at a rate of 1ml per kilogram per hour at least for 8hours before and 8hours after administration of contrast agent. The primary end point was a development of contrast-induced nephropathy (CIN). CIN was defined is an increase of 25% or more in serum creatinine within 2 days after coronary angiography. Results: There were no differences in age, sex, incidence of diabetes mellitus, baseline serum creatinine, creatinine clearance or contrast volume. CIN occurred in 10 of 164 patients (6.1%) in iodixanol group and 18 of 117 patients (15.4%) in ioxaglate group (P=0.013, odd ratio 2.99, 95% confidence interval, 1.262 to 7.127). This difference was more distinct in patients with diabetes mellitus. The occurrence of CIN within the diabetic patients were 5.8% (4/69) in iodixanol group and 21.7% (10/46) in ioxaglate group (p=0.018). And in patients with baseline serum creatinine ���1.4, the CIN after coronary angiography occurred significantly higher in ioxaglate group than in iodixanol group, 25% (12/48) and 8.2% (5/61) respectively (p=0.019). In ioxaglate group, 4.3% of patients had an increase of 1.0mg per deciliter or more, but in the iodixanol group, only in 2.4% patients had. By multivariate analysis, the use of iodixanol was the only risk factor for developing CIN (odds ratio 3.1, 95% confidence interval, 1.27 to 7.53) Conclusion: The incidence of CIN was lower in patients with iodixanol than those with ioxaglate after coronary angiography. This difference was more prominent in higher risk groups.