Effect of contrast material dose on clinically evident change in renal function was studied prospectively in 200 examinations requiring intravenous or intraarterial administration of contrast material. All patients were adequately hydrated. Blood urea nitrogen and serum creatinine were measured before and after the procedure. Ionic and nonionic contrast agents were used. Total dose of contrast material ranged from 30 to 530 mL (mean, 237 mL). There was no tendency to give smaller doses to patients with preexisting renal impairment and no relationship between total dose and patient age. No consistent clinical effect on renal function was demonstrated with increasing dose, regardless of whether ionic or nonionic agents were used. In adequately hydrated low-risk patients with predominantly normal initial renal function and within the dose range studied, there does not appear to be any consistent clinical change in renal function with increasing contrast material dose.