The article represents theoretical substantiation of the problem of the impact connected with traumatic events related to the military conflict in the east of Ukraine, on the psycho-emotional state of the soldiers participating in the antiterrorist operation (ATO). There is analysis of modern scientific researches on the interdependence of combat stress with post-traumatic emotional frustration of fighters, causing: intrusive memories, flashbacks and sleep disturbances; avoidance, manifested in emotional distress, apathy, indifference, despair, depression; hyperactivation, which manifests itself in agitation, intense emotional and physiological excitement, and in unproductive psychomotorism. There is proving of the expediency of psychodiagnostic method «Mississippi Scale» (military option) in the study of symptom complexes: «intrusions» – emotional jostling; «Avoidance» – suppression of traumatic memories; «hypersensitivity» – hypertrophied psychophysiological reactions; feelings of guilt and shame and suicidal inclinations. There is empirical definition of psychological peculiarities of respondents with post-traumatic stress disorder as a kind of neurosis, manifested as a result of the simultaneous experience of several psychotraumatic events by a fighter. There is disclosure of PTSD as a delayed reaction of the individual to a stressful event of a threatening nature, which also caused chronic stress – distress. The psychopathological condition of fighters is revealed, which is caused by the necessity to perform responsible combat tasks under the conditions of extreme ATO factors. There is determination of destructive mental states that are developing in the military and in the period of adaptation to the usual conditions of life and service, after returning from the war that reduces the stress resistance and the process of social adaptation.There is description of stressful factors: high responsibility, danger, death of friends, injury, contusion, disability, long stay in the ATO, etc., which destructively affect the psychological health of the soldiers. The basic psychotherapeutic strategies of psychoanalysis of ATO participants are offered: updating of adaptive skills and renewal of own resources of «I»; formation of «positive attitude» to the symptom; reduction of avoidance, focus on the transformation of psychotraumatic experience; change in the attribution of the content of the traumatic situation and its consequences, the feeling of its own «control and authority over the psychotrauma».