The characteristics of transformation of the psychophysiological state of servicemen during a long stay in the combat zone have been studied. The psychophysiological status of servicemen, muscular strength and endurance of right and left arms were assessed. The obtained results indicate that the studied contingent was heterogeneous in its psychophysiological status and was divided into two subgroups «better» and «worse». It was found that the studied psychophysiological parameters are described by two orthogonal factors (65%) - the «activation and stress of the body» factor (38%) and the «quality of cognitive processes» factor (27%). The first factor is the most powerful, this indicates a significant role of a serviceman’s stress-resistance in the conditions of long stay in the combat zone. It was found that this factor is also the leading one in the «worse» subgroup, this to a lesser extent can prevent disorder and unpredictability of behavioral reactions of combatants. In the «better» subgroup «quality of cognitive processes» was the leading factor. It plays a significant role in the balanced activity of functional systems of the body responsible for formation of adaptive behavioral responses during long-term action of high-level stressors. The decisive rules for selection of servicemen best suited for carrying out official duties in conditions of high-risk activities have been developed.