The aim of this study was to investigate the relationship between oxidative stress and chronic daily headache (CDH) in children. Although there are reports that oxidative injury may play a role in the pathophysiology of some neurologic disorders, such as migraine and epilepsy, by disrupting or destroying cell membranes through the formation of free radical and reactive oxygen species, the pathophysiology of headache is not clearly established. A total of 38 children (16 boys and 22 girls) with CDH, aged between 7 and 15 years, were enrolled in the study. The control group consisted of 39 healthy children (17 boys and 22 girls), aged between 7 and 14 years. The mean age was 10.9 ± 2.2 years for both the groups. Activities of erythrocyte superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) as well as malondialdehyde (MDA) levels in all the children of both the groups were measured. Mean activities of erythrocyte SOD, CAT, and GPx as well as MDA levels were significantly higher in the study group than in the control group (p < 0.001). The findings of this study suggest that oxidative stress may play a causal or consequential role in children with CDH.