Bronchial asthma is a chronic inflammatory disease characterized by bronchial obstruction, usually reversible spontaneously or after therapy, bronchial hyperreactivity and accelerated decrease of lung function that may possibly evolve into irreversible obstruction of the respiratory tract. Bronchial provocation tests can be used in order to assess the presence and degree of bronchial hyper reactivity. The recently introduced mannitol powder inhalation indirect test seems to have an interesting and promising role, especially in childhood, because of its high diagnostic specificity, easiness of execution and best standardization. In this study the authors focused on the significance and clinical use of mannitol bronchial challenge test in asthmatic children.