Respiratory diseases are one of the most common health problems among service personnel assigned to contemporary military operations which are conducted in areas characterized by adverse environmental conditions. This article reviews the results of the studies into the prevalence of acute respiratory tract diseases among soldiers of the Polish Military Contingent deployed to Iraq and Afghanistan. The article also discusses a number of factors which increase the prevalence of diseases diagnosed in the population of soldiers on a military mission in different climatic and sanitary conditions. Retrospective analysis was based on medical records of Polish troops treated on an outpatient basis in Iraq in 2003-2004 (n = 871) and in Afghanistan in 2003-2005 (n = 400), 2009 (n = 2,300), and 2010 (n = 2,500). The intensity rates were calculated and were then used to calculate the prevalence of diseases per 100 persons in a given population of the military personnel. We found that acute respiratory tract diseases were one of the most common health problems treated in outpatient medical facilities in all four study populations. The incidence rate was 45.6 cases in Iraq in 2003-2004, and in Afghanistan it amounted to 61.8 in 2003-2005, 45.3 in 2009, and 54.8-100 persons in 2010. In conclusion, the prevalence of respiratory diseases was closely related to the environmental factors, such as sand and dust storms, extreme temperature changes, unsatisfactory sanitary conditions, and common disregard of basic principles concerning disease prevention.