Background: Contrast media (CM) are nephrotoxic and might further worsen renal function in patients with chronic renal failure. L-Arginine, the substrate of nitric oxide, protects kidney function and may improve endothelial function in patients with coronary artery disease. Hypothesis: Acute administration of L-arginine in a subset of patients with combined coronary artery disease and impaired kidney function during coronary angiography might prevent superimposed acute renal failure. Methods: A double-blind study of patients with mild/moderate chronic renal failure (Cr >1.7 mg/dl) undergoing coronary angiography (meglumine ioxaglate) was conducted. Patients received either L-arginine (300 mg/kg) or placebo and were followed for 48 h. Cardiac hemodynamic parameters, renal function and nitric oxide production were sequentially recorded. Results – Primary and Secondary: Both groups experienced a decrease of creatinine clearance 48 h following the procedure (p < 0.05). Creatinine levels slightly increased following the administration of L-arginine (p < 0.05) but not in the placebo treated group. No changes of systemic and cardiac pressures, total peripheral resistance or cardiac output were recorded within and between the treatment and placebo groups. Conclusion: CM injection causes an impairment of renal function. Addition of intravenous L-arginine during cardiac catheterizations in patients with chronic renal failure does not prevent CM-induced nephrotoxicity and does not affect endothelial dysfunction in the particular population studied by the authors, i.e. patients with coronary artery disease (CAD) of various degrees, or suspicion of CAD and chronic mild renal failure.