Our paper presents microbiological air pollution inside and outside two different poultry farms in Lower Silesia, Poland. The smaller poultry house (A) with 18,000 broiler chickens was surrounded by a protective green tree belt; the larger poultry house (45,000) was surrounded by a field without trees. Air samples were taken at ten sampling sites using a MAS-100 air sampler (Merck) in the summer, autumn, and winter of 2009 and in spring 2010. Seasonal variations were observed in all locations with regard to the numerous microorganisms. According to the Kruskal-Wallis test, the difference between the total number of bacteria in the indoor air of the poultry houses and surrounding area was statistically significant. It has been stated that the total number of heterotrophic bacteria (as CFU/m³) in distant points (10 m, 50 m, 100 m) in summer at houses A and B was higher with regard to Polish Norms and ranged between between 6.0×10³-2.6×10⁴. Moreover, nearly all sampling points in both poultry houses were presumed to be heavily contaminated by staphylocooci (0-1.4×10⁴). In relation to Polish Norms, the air in points situated near the poultry farms can be referred to as highly-contaminated with fungal and bacterial microflora.