The prevalence of various phenotypes of alpha 1-antitrypsin (alpha 1-AT) in the population was investigated and their contribution to the emergence of polypous rhinosinusitis was ascertained. We examined 1738 residents of the Kalinin district, aged 16 to 82 years, 1390 of which were essentially healthy people and 348 of which were patients with polypous rhinosinusitis. We found that among both groups the carriers of normal phenotype MM were in predominance: 96.34% and 94.5%, respectively. We detected infrequent occurrence of heterozygotic phenotypes in the two groups. We demonstrated that, as compared to the healthy population, phenotype MZ occurred more frequently among patients--heterozygotic carriers of alpha 1-AT deficiency gene: 3.16% versus 0.79%, respectively. Thus the risk of polypous rhinosinusitis in them was 4 times higher. We measured alpha 1-AT activity in healthy and affected people--carriers of the normal gene M (PIMM) and found a normal inhibitor concentration (2.2 +/- 0.1 g/l soybean inhibitor) while heterozygotic carriers of alpha 1-AT deficiency showed a moderate decline of the inhibitor concentration: 50% to 82% of the norm. These observations can be used in medicogenetic consultation, professional selection and individual therapy choice.