The outcome of asthma in 406 children, aged 8 to 12 years, was studied. Follow-up in adulthood was 86%, with a mean age of 24.7 years and a mean interval of follow-up of 14.8 years. The predictive value of gender and various childhood variables on the adult level of pulmonary function (forced expiratory volume in 1 second [FEV1]) and bronchial responsiveness in adulthood was assessed. An increase in mean percent predicted FEV1 from childhood to adulthood was found, both in subjects with (76%) and without (24%) current respiratory symptoms. The only childhood variable predictive of adult level of FEV1 was the level of percent predicted FEV1 (p < 0.01). The proportion of subjects with a histamine provocative concentration causing a 10% decrease in FEV1 less than or equal to 16 mg/ml decreased significantly in adulthood. The degree of bronchial responsiveness had increased slightly in adults with symptoms (p = 0.87), whereas it had decreased significantly in subjects without symptoms (p < 0.01). Female subjects were significantly more responsive in adulthood than male subjects (p = 0.047). The childhood degree of bronchial responsiveness significantly predicted the presence of bronchial responsiveness in adulthood (p = 0.02). We conclude that childhood percent predicted FEV1 is relevant to predict the outcome of the adult pulmonary function level, whereas female gender and the childhood degree of bronchial responsiveness are important for the prediction of adult degree of bronchial responsiveness among children with asthma.