The evaluation of S. aureus resident carrier state on the nasal mucosa among school children showed that its intensity was determined by the ecological factors in the place of residence. Under favorable conditions of the central part of the city the level of S. aureus carrier state was 25.4 +/- 3.1%, while in the northern and southern parts of the city, where most of major metallurgical and chemical plants are situated, these values were 44.4 +/- 4.2% and 45.9 +/- 1.6%. The calculation of the factor of staphylococcal resident carrier state (FSRCS), i.e. the ratio of the carrier state levels in the ecologically favorable (control) zone and in the zone under study, revealed that the FSRCS values in the northern and southern zones were 1.81 and 1.74. Thus the ecological situation could be regarded as critical in none of the districts of Volgograd. The levels of S. aureus resident carrier state were highly correlated to the degree of air pollution, evaluated by the factor of total air pollution, and upper respiratory tract diseases in children. The level of S. aureus resident carrier state may be used as a marker in the ecological ranging of the city territories.