In order to determine if respiratory syncytial virus (RSV)-specific IgE responses at the time of bronchiolitis in infancy are related to recurrent wheezing and pulmonary function at 7-8 years of age, a cohort of 43 infants was identified at the time of their initial RSV bronchiolitis episode. RSV-specific IgE responses in nasopharyngeal secretions were determined, and patients were then followed prospectively with notation of the number of wheezing episodes and exposure to cigarette smoke at home. At 7-8 years of age the patients underwent skin testing to 7 environmental allergens and pulmonary function testing, including pulse oximetry and methacholine challenge. Pulmonary function following inhalation of bronchodilating agents was compared to baseline pulmonary function results in order to determine if abnormalities of pulmonary function were reversible. Recurrent wheezing following bronchiolitis was associated with the initial RSV-IgE response, as well as with a family history of asthma. Current wheezing at age 7-8 years was associated with 2 or more positive skin tests (P < 0.01), a history of exercise-induced wheezing (P = 0.01), and increased sensitivity to methacholine (P < 0.01). Pulmonary function test results were similar for groups with and without recurrent wheezing following bronchiolitis. For the entire study group, RSV-IgE specific responses were unrelated to pulmonary function, but small airway dysfunction was associated with passive smoking (P < 0.025), and both large airway dysfunction and increased airway reactivity were associated with the number of positive skin tests (P < 0.025). Reduced small airway function improved following bronchodilator inhalation.(ABSTRACT TRUNCATED AT 250 WORDS)