PURPOSE: To evaluate the nephrotoxicity of Gd-DTPA in rats with normal renal function and in those with acute renal failure, using 0.1mmol/kg and 0.3mmol/kg in each group. MATERIALS AND METHODS: Sixty rats weighing 200-250gm were divided into two groups: normal (N) and glycerol induced acute renal failure (F) ; this was inducedby intramuscular injection of 50% glycerol(10ml/kg). Each group was divided into three subgroups; subgroup 1 was given physiologic saline (0.15 M NaCl) via the tail vein, while subgroups 2 and 3 were given 0.1 mmol/kg Gd-DTPAand 0.3mmol/kg Gd-DTPA, respectively. Blood and 24-hour urine were collected before and on the first and secondday after intravenous injection of either physiologic saline or Gd-DTPA. In order to obtain pathologic specimens, two additional rats in each group underwent the same experimental procedure, and on the first or second day after intravenous injection of saline or Gd-DTPA, both kidneys were removed for light microscopic examination. Serum creatinine (Cr), urine creatinine, and several urinary enzymes such as alkaline phosphatase (ALP), gammaglutamyl transferase (GGT), N-acetyl-Beta-glucosaminidase (Beta-NAG) and lactic dehydrogenase (LDH) of 24 hour urine were measured, and creatinine clearance (Ccr) was calculated. RESULTS: The results were as follows. 1. In the groupwith normal renal function, levels of serum creatinine and urinary enzymes remained unchanged after infusion of 0.1mmol/kg Gd-DTPA or 0.3mmol/kg Gd-DTPA. 2. Among rats with acute renal failure, no difference in serum creatinine and urinary enzyme levels between the saline injection group and 0.1mmol/kg Gd-DTPA injection group was noted. 3. Among rats with acute uremia, Beta-NAG, LDH and ALP were significantly higher on post-injection days 1 and 2 in the 0.3mmol/kg Gd-DTPA injection group than in the physiologic saline or 0.1mmol/kg Gd-DTPA injection group.4. Light microscopic exammination of rats with normal renal function after Gd-DTPA injection revealed no significant pathologic change. Those with acute renal failure rats revealed some degree of vacuolization and/or necrosis of renal proximal tubular epithelial cells. No difference was found, however, between the saline and Gd-DTPA injection subgroups. CONCLUSION: In conclusion, Gd-DTPA was safe in rats with normal renal function, even when the dose was tripled (0.3mmol/kg), and was safe in those with acute renal failure when the standard dose (0.1mmol/kg) was given. In this latter group, however, a triple dose induced some renal damage.