Nasal polyposis (NP) is commonly associated with nonspecific bronchial hyperresponsiveness (BHR) and/or asthma. The aim of this prospective study was to investigate the changes of pulmonary function and BHR in patients with nasal polyposis. Forty-four consecutive patients with NP were included in the study and were followed for 12 mo. Nonspecific BHR was assessed by a carbachol challenge test to determine the provocating dose (PD20) necessary to decrease FEV1 by 20% from baseline values; 17 of 22 patients who demonstrated BHR also exhibited asthma. Spirometric measurements and carbachol challenge were performed before initiating any treatment and 12 mo later. All patients were treated first with beclomethasone (600 microg/d). Intranasal ethmoidectomy was performed in 23 patients who did not improve when treated with topical steroids alone (nonresponders); in contrast, 21 patients were successfully treated with beclomethasone alone (responders). PD20 significantly decreased in the group of nonresponders (p = 0.018), whereas it remained unchanged in responders (p = 0.95). FEV1 (% pred) and FEF25-75 (% pred) significantly decreased in nonresponders (p < 0.001), whether BHR existed or not, whereas no significant change was observed in responders. Our results demonstrate that nonresponders who required nasal surgery exhibited an enhancement of BHR and a slight but significant decrease of FEV1 and FEF25-75 values. However, no change in pulmonary symptoms and/or asthma severity occurred. Clinical and functional follow-up of these patients should assess the long-term evolution of these parameters and their clinical relevance.