Pathogenetic mechanisms and consequences of combat traumatic brain injury (TBI), especially in the acute period, are very complex. They flow at the system and intersystem levels independently or in parallel, and also interact with each other. The aim of this work is to study the electrical activity of the brain, the content of brain-derived neurotrophic factor (BDNF) in blood serum and cerebrospinal fluid (CSF) and their interaction with neurophysiological parameters in patients with contusion and concussion in acute mild combat TBI. An increase in the spectral power of the slow frequencies of the delta and theta ranges on the electroencephalogram (EEG) was found in patients with cerebral contusion (11 people). Along with similar changes, an increase in the spectral power of the alpha rhythm was found in patients with concussion (19 people). The control group included 9 practically healthy men. An increase in the spectral power of oscillations of beta 1, beta 2 frequency ranges in the left hemisphere in patients with cerebral contusion was positively correlated with the level of BDNF in CSF. Different directionality of BDNF changes in blood serum and CSF in patients with cerebral contusion and brain concussion was revealed: an increased level of BDNF in serum compared to control, and a decreased level of BDNF in CSF in patients with brain concussion compared to contusion group, with no changes in serum compared to control and an increase in the level of BDNF of almost 2.5 times in CSF in patients with cerebral contusion compared to concussion group. The data are considered from the point of view of greater preservation of the blood-brain barrier (BBB) and associated compensatory metabolic processes in patients with concussion, compared to contusion group in the acute period after mild combat TBI.