Our knowledge about the age-related growth of pulmonary function is incomplete. The purpose of this study was to describe the relation of various factors to the growth of pulmonary function in children and adolescents. A population sample comprising 408 children and adolescents (7-17 yr of age at enrollment) was reexamined after a 6-yr interval. Case history was obtained by interview and questionnaire. Pulmonary function, skin prick test reactivity to common allergens, and airway responsiveness (AR) were measured using standard techniques; airway hyperresponsiveness (AHR) was defined as a concentration of histamine causing a 20% decline in FEV1 < 8 mg/ml. The cross-sectional analyses of data from the two surveys showed that the presence of asthma (p < 0.02), atopy to house dust mite (HDM) (p = 0.03), and increasing degree of AR (p < 0.002) were associated with a lower level of FEV1 %pred. The longitudinal analysis revealed that asthma (p = 0.0001) and a lower level of FEV1 (p < 0.0001) at enrollment were associated with a lower level of FEV1 at follow-up. Further, an increase in the degree of AR (p = 0. 0001), new asthma (p = 0.0002), and new atopy to HDM (p = 0.03) also predicted a lower level of FEV1 at the end of the observation period. Confining the analysis to subjects without asthma and without evidence of AHR (n = 271) showed that both persistent (p = 0.04) and new (p = 0.03) atopy to HDM predicted a lower level of FEV1 at follow-up; compared with subjects with a negative skin reaction to HDM, those subjects who were sensitized to HDM had on average a 5%pred lower level of FEV1. The growth of FEV1 in children and adolescents appears to be impaired not only by symptomatic asthma but also by an increase in the degree of AR and atopy to HDM; sensitization to HDM appears to have a negative impact on the age-related growth in FEV1 even in nonasthmatic subjects without evidence of AHR.