OBJECTIVE: To study the change and significance of ionic calcium (Ca 2+ ) in renal tissues of the neonatal rat after asphyxia. METHODS: Forty five 7-10 day neonatal Wistar rats were randomly assigned into 4 groups: the non asphyxiated controls (n=13), 2 h post asphyxia (n=10), 24 h post asphyxia (n=11) and 48 h post asphyxia (n=11). The animal model of the three experiment group was established by normobaric asphyxia. The left renal coefficient (LRC) was calculated; the content of Ca 2+ in the renal tissue was detected; and the scores of tubular injuries were evaluated under the light microscope at 2, 24 and 48 h after asphyxia. RESULTS: The LRC [( 7.64 ± 0.33 ) g/kg], the scores of tubular injuries ( 28.80 ± 7.16 ) and the content of Ca 2+ [( 1.75 ± 0.39 ) mmol/g] in the renal tissue obviously increased from 2 h of post asphyxia compared with the controls [( 4.88 ± 0.90 ) g/kg; ( 5.46 ± 1.76 ); ( 1.44 ± 0.46 ) mmol/g] (P< 0.05 ); and the scores of tubular injuries and the LRC reached to the peak at 24 h of post asphyxia. The content of Ca 2+ in the renal tissue was positively correlated with the LRC at 2, 24 and 48 h of post asphyxia (r= 0.61 , 0.69 , 0.63 , respectively; all P< 0.05 ). It was also positively correlated with the scores of tubular injuries at 2, 24 and 48 h of post asphyxia (r= 0.57 , 0.58 , 0.75 , respectively; all P< 0.05 ). CONCLUSIONS: Ca 2+ may play a role in the development of renal injuries following asphyxia.