The present study included 37 patients at the age from 18 to 65 years suffering polypous rhinosinusopathy (PRS). Endoscopic examination of their nasal cavity and anterior rhinoscopy revealed the presence of large- and medium-sized polyps (stages II-III according to the classification of G.M. Portenko).. All the patients were treated with longidase either injected directly into the polyps at a dose of 3,000 IU or used to irrigate the affected nasal mucosa (10 seances). Positive effect of the treatment was documented in 32 (86%) patients of both groups who reported restoration of nasal breathing, showed improved functional characteristics, and significantly reduced size of local polyps upon the endoscopic examination of the nasal cavity. It is concluded that longidase is an efficacious and safe preparation for the conservative treatment of polypous rhinosinusitis.