The theme of the final work is stress in Modern Military Operations. Work is conceived through six units. In the first set, the concept of stress is defined, while in the second one it is shows an overview of Modern Military Operations. The third is the list of challenges and threats encountered by the mission participants before, during and after the mission. The fourth unit defines the underlying terms of combat stress, symptoms of combat stress, behaviour in battle reaction and types of combat stress, while the fifth is focused on psychological pre-mission prevention and psychological support during and after the mission. The final set is not of a theoretical character, but a questionnaire has been conducted on twenty-four Croatian military members to determine the extent to which it is demanded an adaptation to return to the everyday family, work and social environment. Based on the results obtained, it was found that the participants of the mission had difficulties in adapting to the everyday family, working and social environment.