Three bronchoconstrictive responses associated with acute rhinitis and occurring in two patients were observed among 400 nasal allergen challenges. Causative substances were birch pollen, Dermatophagoides pteronyssinus and HSA-conjugated pyromellitic dianhydride. Both subjects showed bronchial hyperreactivity and immediate-type sensitization to these allergens. It is concluded that bronchoobstruction nearly occurs in nasal allergen challenges. The underline pathophysiological mechanism remains unclear.