Levels of antibodies AB (AB) to S100B and S100B protein were studied in the blood serum of children with different severity and outcomes of traumatic brain injury (TBI) from the 1st to 15-75th days after TBI. Severity and outcomes were assessed using the Glasgow Coma Scale (GCS). Patients were stratified by outcomes into the following groups: complete recovery (group 1), moderate disability (group 2), high disability (group 3), vegetative state (group 4) and fatal outcome (group 5). In patients of groups 1-3, the changes of S100B in the blood serum didn't depend on the severity of brain's damage; the significant increase of S100B protein levels in the 1st day was accompanied by the decrease to the normal range in the following 2-3 days. On the contrary, the levels of nAB in these groups increased starting from 3-5 days corresponding to the severity of brain's damage. The development of vegetative state was accompanied by low S100B and high AB to S100B levels in the blood serum. The maximal level of S100B protein and increased levels of AB were observed in patients with fatal outcome. In most patients with combined TBI, the levels of both parameters were higher compared to those with separate TBI.