OBJECTIVE: To study the changes in Nacety-β-D-amino glucosidase (NAG) and urinary retinal binding protein (RBP) observed after renal function impairment in asphyxiated newborns. METHODS: Colorimetry of p nitrophoenol and ELISA were adopted to detect the activity of NAG and the content of RBP in asphyxiated full term and premature infants on days 1, 3 and 7, and in matched nonasphyxiated control infants. RESULTS: The levels of NAG and RBP were higher in both asphyxiated full term and premature infants than in the control group (P<0.01). The changes were most significant on day 3 after birth, and correlated with the degree of asphyxia. The degree and duration of renal dysfunction also correlated significantly with the degree of asphyxia. Urinary RBP levels in the asphyxiated newborns rose significantly within 1 day after birth compared to the controls (P<0.01), while there was no significant difference in the levels of NAG on day 1 of life in asphyxiated infants (P>0.05). CONCLUSIONS: NAG and RBP appear to be indexes of early diagnosis in renal dysfunction in asphyxiated infants, and RBP is a more sensitive one.