Copeptin is a hypothalamic stress hormone that is synthesized in the hypothalamus together with Arginine-vasopressin and circulated from the neurohypophysis in equimolar amounts and can indicate the individual stress level. The aim of this study was to investigate the plasma copeptin level for childhood migraine headache. In this study, total oxidant status (TOS); total antioxidant status (TAS); oxidative stress index (OSI); and copeptin were measured in the plasma samples of 61 migraine patients and 60 matched healthy participants. The median plasma copeptin levels in the patients group and control group were 298.25 and 194.35 pg/mL, respectively. Copeptin levels were significantly higher in migraine patients than in the healthy control group. The specificity and sensitivity of copeptin for 249.5 pg/dL cut off value predicting diagnosis of migraine were 67% and 64%, respectively. In addition, TOS and OSI levels were found to be higher and TAS levels were significantly lower in patients with migraine than healthy controls. Plasma copeptin levels are thought to increase in cases of childhood migraine secondary to increased oxidative stress. In the diagnosis of childhood migraine cases, it can be used together with oxidative stress biomarkers such as TAS, TOS and OSI as a complementary parameter.