Previous studies have reported a 4%-50% incidence of acute renal failure (ARF) following the use of radiocontrast media in patients with preexisting chronic renal insufficiency. In these studies, ARF was defined as a rise of the serum creatinine of at least 1 mg/dl above baseline. Using the same criteria, we studied 214 patients undergoing various intravascular radiocontrast media procedures. Patients were infused with a specially prepared cocktail solution (NSMF) containing 1000 ml half-normal saline, 12.5 g of mannitol (M), I ampule NaHCO3, and 200 mg of furosemide (F) at 100 ml/h from one hour prior to two hours after the procedure. Urinary output was replaced with normal saline for at least 6 h after the procedure. Seven percent of the patients developed acute renal insufficiency. Only 3% of the patients had a rise in serum creatinine greater than 2 mg/dl. No patient required dialysis therapy after the procedure. There was one unrelated death caused by acute myocardial infarction postangioplasty. Risk factors for development of ARF despite cocktail administration included the presence of diabetes mellitus and angiotensin converting enzyme (ACE) inhibitor therapy. We concluded that the properly administered NSMF solution protects against radiocontrast dye induced renal failure. In select patients with chronic renal insufficiency, consideration should be given to withholding ACE inhibitor therapy for 24-48 h prior to administration of intravenous radiocontrast dye. A large controlled trial will be required to establish whether the NSMF solution offers benefit beyond that of saline hydration alone.