Interleukin 8 (IL 8) which is released from inflammatory cells during the ischemia/reperfusion process can cause cell damage. This paper aims at studying whether IL 8 is involved in the brain ischemia/reperfusion injuries in the neonates with hypoxic ischemic encephalopathy (HIE). Methods Serum IL 8 levels were detected using enzyme linked immunoabsorbent assay (ELISA) in 50 neonates with HIE, 20 neonates without HIE but with infectious diseases and 30 normal neonates. Results Serum IL 8 levels in neonates with HIE ( 21.52 ± 9.59 pg/ml ) were significantly higher than those in the normal cases ( 14.43 ± 4.84 pg/ml )(P< 0.01 ). Serum IL 8 levels were related to the severity of HIE. The more severe the HIE, the higher the serum IL 8 levels. However, a significant difference was noted only between the mild and severe HIE cases ( 17.56 ± 6.52 pg/ml vs 26.07 ± 13.83 pg/ml ; P< 0.05 ). After a regular 2 week treatment of HIE, serum IL 8 levels decreased significantly compared with those of before treatment ( 14.53 ± 4.87 pg/ml vs 22.60 ± 7.06 pg/ml ; P< 0.01 ). Serum IL 8 levels in HIE neonates complicated by infectious disease ( 23.97 ± 11.04 pg/ml ) were higher than those in HIE neonates without infections ( 18.38 ± 6.07 pg/ml ) and also higher than those in neonates with infectious disease but without HIE ( 18.22 ± 8.01 pg/ml )(both P< 0.05 ). Conclusions IL 8 appears to be involved in the brain injuries of HIE. The detection of serum IL 8 levels may be of value in the diagnosis of neonatal HIE and in the assessment of its severity. There findings can then be used as guidelines for its treatment.