Bronchial asthma and allergic rhinitis often co-exist, and rhinitis is a major risk factor for the development of asthma. However, the reported incidence of allergic rhinitis in asthmatic children varies widely. The aim of this study was to elucidate the incidence of allergic rhinitis, the onset age of chronic upper and lower airway symptoms, and the correlation of these two symptoms in asthmatic children. A cohort of 130 consecutive children (ages 2-10) with asthma was evaluated. A questionnaire regarding upper and lower airway symptoms was filled out by the parents. Objective diagnosis of allergic rhinitis was also made on the basis of rhinoscopy, nasal cytology, nasal challenge, and specific serum IgE (CAP-RAST). Persistent nasal symptoms were present in 83.8% of the asthmatic children. The incidence of allergic rhinitis was 77.7% based on the objective findings. The mean onset age of asthma was 2.8 yr, and that of rhinitis was 2.9 yr. Nasal symptoms started as early as the first year of life in 8.9% of the children. In children with comorbid asthma and allergic rhinitis, rhinitis preceded in 33.7%, asthma preceded in 31.7%, and both started in the same year in 26.7%. In 7.9%, rhinitis was asymptomatic. Concomitant exacerbation of the upper and lower airways occurred in 34.6% of the total 130 children. These results demonstrate that allergic rhinitis manifested early in life in the majority of the asthmatic children. Persistent nasal symptoms in infancy may point to subsequent development of asthma and possible early intervention.