PURPOSE: This study was conducted to evaluate the effect of IVIG infusion on renal function in VLBW infants. IVIG has been proved quite safe in neonates given prophylactic and therapeutic doses. But nephrotoxicity is not recognized as adverse in IVIG therapy, only several previous adult cases have been noted. METHODS: For a total of ten VLBW infants who had not been received any medication except parenteral nutrition, vitamin and Fe supplements was assigned for study. To observe changes in renal function after preventive dose of IVIG administration(500mg/kg, 1dose) serum BUN and creatinine, 2-microglobulin( 2-MG) and N-acetyl- -D-glucosaminidase(NAG) were obtained prior to study and 1, 3 and 7 days after infusion. RESULTS: 1) There were no elevation of serum BUN and creatinine after IVIG administration, 2) There was transient increase of urine NAG from 1.1+/-0.7 u/mg creatinine before infusion to 2.7+/-5.3 u/mg creatinine on the first day of infusion, which was not statistically significat, decreasing to pretreatment level on the 3rd and 7th days after infusion. 3) There was transient increase of urine 2-MG from 294.6+/-223.8 microgram/mg creatinine before infusion to 680.0+/-108.9 microgram/mg creatinine on the first day and 416.0+/-246.3 microgram/mg creatinine on 3rd day after infusion, which was not statistically significant. CONCLUSIONS: It was found that prophylactic dose of IVIG in VLBW infants does not cause clinically significant impairment of renal function. but mild increment of urine NAG and 2-MG may suggest the possibility of renal tubular damage. Based on these results, further evaluation of the effect of IVIG on renal function in VLBW infant is recommended.