The military forces usually conjure up the image of soldiers who serve in a given country, or those who carry out their duties in peacekeeping missions. They are frequently in the spotlight during their stay in the area of their operations and the performance of their duties. The memories of them and of any of the possible problems that they may encounter usually fade away once they have gone back to their country, or once they have returned to their parent unit. Interestingly, this rule also applies to other members of the military personnel. Service in the army, which frequently implies exposure to atrocities and ongoing hostilities, undoubtedly leaves its mark on people’s physical and mental health, and it can also have a major impact on the lives of professional soldiers and their families. Paradoxically, the level of stress experienced increases as the sense of a real threat goes down. Being a soldier is one of those professions in which exposure to stress is high, and there is a major risk of post-traumatic stress disorder (PTSD), especially in those members of the armed forces who have taken part in foreign missions. This paper looks at the historical background of the phenomenon, its symptoms, its methods of diagnosis, as well as the entire system of monitoring, supporting and treating post-traumatic stress in the Polish Armed Forces. Such a study has been possible thanks to a thorough analysis of the applicable pieces of legislation, backed by an insight into a series guidelines, orders and dispositions given at all levels of command and supervision in the army.