Allergic rhinitis is currently considered the most common allergic condition. The ECAP (Epidemiology of Allergic Disorders in Poland) study, which was conducted in Poland between 2006 and 2008, found that allergic rhinitis affects 23.6% of children aged 6–7 years, 24.6% of children aged 13–14 years and 21.0% of adults aged 35–44 years. It was shown that allergic rhinitis causes a nine-fold increase in the risk of allergic asthma. The aim of the study was to assess the risk of asthma in children with allergic rhinitis based on spirometric identification of bronchial obstruction. A three-year follow-up was conducted in a group of 60 children, including 37 study patients with diagnosed allergic rhinitis and 23 controls. Three (8.1%) children in the study group developed asthma. Despite normal spirometry findings in the three asthmatic children with allergic rhinitis, comparison analyses indicated statistically significant differences in FEV₁ and FVC values between the study group with allergic rhinitis and asthma and the controls. Normal spirometry results in most monitored children, suggesting the absence of lower respiratory inflammation, may be associated with an adequate control of allergic rhinitis as a result of proper treatment.