Effects of dietary probucol on renal damage induced by a renal carcinogen, ferric nitrilotriacetate (Fe-NTA), in male Wistar rats were quantitatively investigated with a computer-mediated image analyzer. The kidneys of rats fed a 1% probucol diet were protected from necrosis and lipid peroxidation induced by a single i.p. treatment with Fe-NTA solution at 5 mg Fe/kg body wt and were significantly resistant to a higher dose. For the parameter of lipid peroxidation, Schiff's staining method was utilized to demonstrate the extent of formation of aldehydes, products of lipid peroxidation. Thus following injection of Fe-NTA solution at 10 mg Fe/kg body wt the average areas of tubular necrosis were 85.8% versus 56.9% and the positive areas for Schiff's staining were 15.3% versus 5.6% in the renal cortices of rats fed control of 1% probucol diets respectively. These results indicate that probucol provides protection against Fe-NTA-induced nephrotoxicity through its antioxidant properties. In addition to being a cholesterol-lowering drug, useful for the control of hypercholesterolemia, probucol may therefore be beneficial for prevention and treatment of various pathogenic processes including those leading to carcinogenesis.