Nasal polyposis is in 25-70% complicated by the development of bronchial asthma, its attribute being bronchial hyperreactivity (BH). The authors examined 101 patients (23 with polyps and asthma, 53 with polyps and 35 controls) using the standard bronchoconstriction test as described by Cockroft and Vondra). By inhalation of increasing concentrations of histamine solutions the provoking concentration, PC20, was assessed. In the group with polyps and asthma 56% patients suffered from spontaneous bronchial obstruction and 44% from high and medium BH (PC20 less than 1.0 mg/ml). In patients with nasal polyposis alone in 21% spontaneous obstruction was found or a high BH, similarly as in the group suffering from asthma (PC20 less than 0.5 mg/ml). A medium BH was recorded in 23% and a mild BH in 26% (PC20 less than 1-2 mg/ml). 30% of patients with polyps are normoreactive (PC20 greater than 2 mg/ml). In the control group all patients were normoreactive. Patients with polyps and a high or medium BH are a risk group (44% of patients) threatened by the development of asthma. They call for longitudinal follow up of the BH and frequent check-up examinations by an ENT specialist and allergologist. Many years' verification of this hypothesis and evaluation of other risk factors is necessary for a more detailed analysis of the risk group of patients with polyps.