Thirty-four case notes of patients in acute renal failure on whom intravenous urograms (IVU) were performed, were reviewed. All patients received high doses of Conray 420 or Urotrast. Delayed films up to 48 hours were routinely done in patients suspected of having obstruction. There were no side effects of the intravenous urogram examination. IVU with high dose contrast material and nephrogram are helpful in differentiating the cause of the acute renal failure, and in excluding outflow obstruction.