PURPOSE: This study was aimed at determining whether tri-iodinated compounds with greater solubility and low osmolality, Na or meglumine ioxaglate(Hexabrix 320, Guerbet Lab., France) had deleterious effects on renal function after cardiac angiography for the evaluation of congenital heart disease(CHD) and determining whether correction of dehydration using iv hydration given before cardiac angiography were effective in prventing renal dysfunction. METHODS: For the study of radiocontrast media induced nephrotoxicity, 21 children with various CHDs admitted to the hospital for the evaluation of their CHDs. None of them had any evidence of renal dysfunction before study. They were devided into 2 groups, one was low-dose group(ioxaglate given, < 2.0 mL/kg) and the other one was high-dose group(>2.0 mL/kg). Renal function studies including serum creatinine(Scr), fractional excretion of sodium(FENa) and urinary beta2-microglobulin excreton(mg of beta2- microglobulin per gm creatinine) were done before and after ioxaglate administration. For the study of hydration effect on radiocontrast media induced nephrotoxicity, 9 children with CHDs were subjected. Thery were hydated with 5% D/S 1 hr before cardiac angiography using high-dose ioxaglate(> 2.0 mL/kg) and maintained on fluid therapy during the examination. Renal function studies were done before and after ioxaglate administration. Statistical analyses were done using Wilcoxon signed rank test. RESULTS: 1) Scr level and FENa were not increased significantly after administration of ioxaglate in both of low-dose and high-dose group. 2) A significant increase of urinary beta2M per creatinine excretion(mg/gm creatinine) was observed after administration of ioxaglate n the high-dose group(0.24 vs 0.57, p<0.01) but, not in the low-dose group(0.28 vs 0.35, p>0.05) 3) Hydration before ioxaglate administration made urinary B2M per creatinine excretion insignificant even in patients who received high-dose ioxaglate, more than 3.0 ml/kg(0.22 vs 0.27, p>0.55). 4) Uric acid and/or calcium oxalate crystaluria appeared after ioxaglate administration, particularly in patients with dehydration. CONCLUSIONS: Ioxaglate, a low osmolality ionic dimer contrast media, could induce renal tubular dysfunction, which depended on dose used. Correction of dehydration before ioxaglate administration significantly reduced the risk of ioxaglate induced nephrotoxicity.