Twenty patients were selected on the basis of perennial rhinitis, the absence of allergy and with an eosinophil count higher than 20% of total leucocytes in nasal secretions (NARES). Nasal endoscopy with biopsies from the middle turbinate and sinus CT were performed. Biopsies were processed for histological examination and for immunofluorescence. The clinical progress during treatment was scrutinized. An acute congestive aspect of the nasal mucosa was noted in 4 cases, and micropolyposis in 9 cases. Sinus CT showed opacity of the ethmoidal cells in 87% of cases (maxillary sinuses: 75%; frontal sinus: 46%; sphenoidal sinus: 31%). An eosinophilic infiltrate of the nasal mucosa was constituted in 9 cases: In 6 cases, the cells expressed the Fc epsilon RII receptor, recognized by the monoclonal antibody Bb10. Anti-H1 drugs usually failed to result in a clinical improvement and local eosinophilia was not changed. Local corticoids were more effective but not sufficient in some cases, so that oral corticotherapy was needed. Ethmoidectomy was performed in three cases. NARES seems to evolve in three stages: (1) migration of eosinophils from the vessels to the secretions; (2) retention of eosinophils in the mucosa which might be linked to activation of unknown origin; (3) nasal polyposis. Numerous interactions between irritation of the epithelium, release of substance P, and eosinophils, lead to the hypothesis of a neurogenic origin of NARES.