Salbutamol diskus (SD) and formoterol turbuhaler (FT) are both fast-acting beta(2) agonists delivery systems used to relieve bronchoconstriction, such as that which accompanies acute exacerbations of asthma. Although SD (which is used only on an as-needed basis) is flow independent, the FT (currently recommended for regular therapy) requires a forceful deep inspiration. Thus, the efficacy of FT in children with bronchoconstriction may be inferior to that of SD. We have studied the bronchodilatation response induced by FT after a standard adenosine-5-monophosphate (AMP) bronchial challenge, and compared it to that induced by SD, and placebo. Seventeen children (mean age +/- SD 10.3 +/- 1.7 y) with asthma underwent three AMP challenges, each time followed by inhalation of either placebo, SD (200 mug) or FT (9 mug), in random order. Patterns of bronchodilatation (forced expiratory volume in 1 second recovery) to 90% of baseline levels were compared. Both SD and FT were significantly better than placebo. FT was slightly better than SD, but this difference was not statistically significant. FT and SD are both effective bronchodilators and may be of comparable efficiency during acute bronchoconstriction in young children with asthma.