Background: In neonates, cerebral hypoxic-ischemia is the main cause of brain oedema which results in neurodevelopmental disfunction. After cerebral injury, Aquaporin-4 (AQP4) is reported to be overexpressed in the astrocytes. This study was conducted to evaluate using of the blood level of aquaporin-4 in diagnosis of hypoxic ischemic encephalopathy in neonates. Methods: Blood samples were collected from 30 neonates with hypoxic ischemic encephalopathy (HIE), sample (1) at age of 2 days while sample (2) at age of 7 days, and from 30 neonates control groups. The collected blood samples were used to measure aquaporin-4 level and creatine phosphokinase (CPK). Results: Aquaporin-4 at age of 2 days was found to be significantly higher in hypoxic patients than the control (220.83±98.85 vs. 135.51± 28.32 pg/ml). Moreover, the level of AQP4 at age of 7 day was 349.72±110.25 pg/ml. There was no significant difference in AQP4 level between preterm and full term hypoxic patients at age of 2 days, as the values were 275.33±69.72 pg/ml for preterm and 214.55±97.06 for full term. However, there was a significant difference in AQP4 level between preterm and full term hypoxic patients at age of 7 days, as the values were 453.93±66.19 pg/ml for preterm and 339.93± 108.22 pg/ml for full term. At age of 2 and 7 days, the severe hypoxic patients had significantly higher AQP4 levels than moderate or mild hypoxic patients. Conclusions: The obtained results indicate that serum Aquaporin-4 level and CPK enzyme activity could be used as early predictors in diagnosis of HIE.