Until now very few studies have been performed on the prevention of exercise-induced asthma (EIA) in children with ipratropium bromide + fenoterol. This is why we decided to study 30 children aged between 6 and 15 years, whose EIA was confirmed by a test including a 6-min free race on day 1 of the study. The criterion was a decrease of more than 20% of the basal values of forced expiratory volume in 1 s (FEV1) or FMF. Children whose FEV1 or FMF baseline values were under 60% of those expected according to Polgard tables were excluded. Three tests were performed, the first to determine EIA, the second was performed 72 h later after inhalation of placebo. 72 h after day 2 the patients returned in order to repeat the test, but this time, aerosol therapy with the combination ipratropium + fenoterol was applied prior to the race. The dosage of the combination was 1 puff of aerosol per 10 kg body weight, up to a maximum of 4 puffs. Each puff of the combination contains 0.02 mg of ipratropium bromide and 0.05 mg fenoterol. Functional assessment of children was carried out by means of forced spirometry. There were no significant differences between the placebo group and the group which received no medication, but there was a significant difference between the treated group and the other two, not only in the FEV1 and FMF values but also in forced vital capacity TEST.(ABSTRACT TRUNCATED AT 250 WORDS)