Hypoxic-ischaemic injury in the developing brain is one of the major causes of mortality and morbidity during birth asphyxia. We estimated lipid peroxidation (LPO) and two key antioxidants viz. superoxide dismutase (SOD) and glutathione peroxidase (GPX) in 34 neonates suffering from birth asphyxia, and in 25 age-matched controls, to investigate the possible role of free radicals in cerebrospinal fluid (CSF) in birth asphyxia. Total calcium and creatine phosphokinase (CPK) were also estimated to determine the extent of brain damage. We categorized the patients into mortality, morbidity and recovered groups according to clinical, biochemical, radiological investigations and death reports. LPO levels were significantly raised in each of these groups. CPK activity was markedly elevated in the mortality group as compared to the control and morbidity groups. Total calcium was raised in the mortality group as compared to controls and recovered group only. SOD activity was highly elevated in both mortality and morbidity groups, whereas GPX activity was significantly lower in the morbidity and recovered groups as compared to the controls. The increased level of LPO suggests that the higher production of free radicals may cause cellular damage in the brain, which was evident from the elevated activity of CPK and level of total calcium. The raised SOD activity also suggests higher production of superoxide anions, whereas the lower GPX activity indicates the accumulation of free radicals, resulting in higher lipid peroxidation in the CSF. (C) 1998 Chapman & Hall Ltd.