Background: The allergic reaction is characterized by an inflammatory response, which is correlated to the allergen exposure, and is detectable in mite allergic patients, even when symptoms are absent. Objective: The study was aimed at assessing the presence of inflammation in patients with pollen allergy during a long observation period. Methods: Six patients, sensitized only to Betula alba, were enrolled. Evaluated parameters were (1) nasal symptoms, (2) inflammatory markers (ie, neutrophil and eosinophil number and intercellular adhesion molecule-1 expression on nasal epithelial cells), and (3) pollen count. Patients were examined during the pollen season every 4 days for 40 days and were observed 3 times after the pollen season. Results: A significant inflammatory reaction was evident throughout the pollen season, even during the days with a low pollen count and low or absent symptoms. Conclusions: The results of this study indicate that the global therapeutic strategy for allergic rhinitis should be revised and targeted to inflammatory phenomena rather than to symptoms alone. (J Allergy Clin Immunol 2000;105:54-7.)