To assess the influence of environmental exposure to tobacco smoke on the nasal symptoms and nasal resistance of young patients with perennial allergic rhinitis.Cross-sectional study.Tertiary referral centre.Fifty patients were evaluated (aged 10-19 years old): 25 patients with and 25 patients without recent exposure to tobacco smoke (confirmed by cotinine/creatinine ratio).After a clinical evaluation, all the patients replied to a validated questionnaire of the severity of the nasal symptoms. Then total nasal airway resistance was recorded by active anterior rhinomanometry.Patients with exposure to tobacco smoke had a larger total resistance than patients without exposure (t-test, P < 0.01). No significant correlation was observed between the total score of the questionnaire of nasal symptoms and the nasal resistance.In young patients with perennial allergic rhinitis, exposure to tobacco smoke can be related to increased nasal resistance, which may not be recognised by the report of nasal symptoms.© 2011 Blackwell Publishing Ltd.