 The prevalence of airway hyperresponsiveness AHR is very high in elite swimmers, reaching 80 in certain studies. Repeated Chlorine-derivatives exposure may be a major causative factor for its development. Asthma diagnosis is generally made on the basis of clinical characteristics. The demonstration of a variable bronchial obstruction through positive expiratory flow reversibility to a bronchodilator, spontaneous variations of airway obstruction or a positive provocation test methacholine, eucapnic voluntary hyperpnoea... is necessary to avoid false diagnosis. Currently asthma treatment in swimmers is the same as in the general population. A short-acting bronchodilator is often prescribed to avoid occasional symptoms, combined with an inhaled corticosteroid or an antagonist of Leukotriene if asthma symptoms are persistent. Previous studies have shown a reduced efficiency for asthma medication in elite athletes compared with non-athletes. The specific response to different medications remains to be studied in athletes. The effects of a short-acting bronchodilator in swimmers with AHR, especially when asymptomatic, on pulmonary function and performance have not yet been studied. Moreover, the significance of a positive bronchial provocation test remains to be studied in asymptomatic swimmers with AHR. 