Combat traumatic brain injury (cTBI) is characterized by the complexity of pathogenetic mechanisms, caused by the combination of the action of factors of mine-blast damage with the psycho-emotional reaction of the body to stress. The consequences of cTBI are manifested in changes in elec- trogenesis and neurochemical parameters of functional and metabolic activity of the brain, one of the important factors of which is cerebral cortisol levels. Identifying the nature of these changes is necessary to improve the effectiveness of therapy and rehabilitation of combatants. The study aimed to identify the features of brain electrogenesis and its relationship with the temporal dynamics of cortisol levels in the blood serum and cerebrospinal fluid (CSF) of combatants with brain con- tusion after cTBI23 patients with TBI were examined (10 in the acute and 13 in the intermediate periods after the injury), whose electroencephalograms (EEG) were recorded, and their visual, spectral, and coherent analyses were also performed. The cortisol levels were determined in CSF and serum by enzyme-linked immunosorbent assay. The EEG spectrograms revealed an increase in the spectral power of Δ-range oscil- lations in the frontotemporal and central brain regions with the development of the consequences of сTBI over time. The spectral power of β-range oscillations in the intermediate pe- riod after the injury decreased compared to the acute period. Cortisol levels in CSF and serum increased over time after cTBI. The level of the hormone in CSF in the acute period after trauma was positively correlated with the spectral power of the biopotentials of the Δ-, θ-, and β-ranges. In the intermediate period, the degree of correlation of cortisol concentration with the spectral power of the biopotentials of the θ- and Δ-ranges decreased, but increased in the β-range. Thus, the EEG of combatants revealed an increase in the spectral power of slow rhythms with impaired intra- and interhemispheric neural com- munication, an increase in cortisol levels in CSF and serum over time, and its positive correlations with the biopotentials of the β-ranges against the background of a weakening, with the biopotentials of slow rhythms.