BACKGROUND: The decongestion test involves spraying an intranasal vasoconstrictor drug to evaluate the recovery of nasal airflow. OBJECTIVE: The aim of this study was to assess the relationship between pulmonary function (assessed by spirometry and methacholine challenge) and nasal airflow recovery after a topical vasoconstrictor had been administered in patients with allergic rhinitis (perennial, seasonal, or mixed allergic rhinitis). METHODS: A total of 150 subjects were studied. The total symptom score, sensitization, and pulmonary function Were all assessed. All Subjects underwent rhinomanometry and the decongestion test. RESULTS: Univariate analysis revealed that nasal symptoms and spirometric parameters (except FEF25-75 in subjects with seasonal allergic rhinitis) were not. Only bronchial hyperreactivity, assessed by methacholine challenge, proved to be significantly (and independently) associated With Outcome (OR 1.45, P = 0.025). CONCLUSIONS: This study provides the first evidence of in association between it positive response to the decongestion test and bronchial hyperreactivity, assessed by methacholine challenge, in patients with allergic rhinitis.