BACKGROUND Renal involvement is frequent in neonates with perinatal asphyxia. It is correlated with the severity of neurological damage and seems to worsen the long-term neurological outcome. OBJECTIVE The aim of this study was to determine the incidence of renal failure after perinatal asphyxia, to precise the relationship between severity of cerebral damage and renal failure and to evaluate the place of renal damage in the short- and middle-term neurological outcome. METHODS We conducted a prospective study including 87 full-term neonates admitted in the neonatology department of F. Hached university hospital in Sousse (Tunisia) and suffering from hypoxic ischemic encephalopathy from 1st January 2003 to 30 June 2005. Renal function was assessed by measuring plasma urea and creatinine at age 48 h. Renal failure was defined by a level of creatinine above 90 micromol/l. Neurologic examination was performed on day 7. The survivors were followed up by the same senior after discharge. RESULTS During the study period, 87 full-term neonates were admitted for hypoxic ischemic encephalopathy. The degree of neurological impairment was determined according to Sarnat classification: 1st stage 9 neonates (10,3%), 2nd stage 67 (77%) and 3rd stage 11(12,6%). Renal failure involved 15 neonates (17,2%) of whom 10 belonging to the 2nd stage group. Renal function outcome was favorable in all survivors with normalisation of plasma creatinine level between day 5 and day 15. Eight neonates died, of whom 3 with renal failure. Neurologic examination was abnormal in 36 out of 72 (50%) neonates without renal failure and in 9 of the 12 (75%) survivors with renal failure. Among the 12 neonates with renal failure, 7 had abnormal neurologic features at discharge. Neurologic assessment between 6 and 18 months was abnormal in 4/12 (33%) of neonates with renal failure versus 8/72(11%) of neonates without renal failure. CONCLUSIONS Transient renal failure is commonly observed in perinatal asphyxia. Renal failure is correlated with neurologic severity. Renal function assessment using creatinine plasma level seems to be correlated with neurologic outcome. However, other tools appreciating renal function, namely tubular function, should be determined earlier in order to predict neurologic outcome after hypoxic ischemic encephalopathy.