Short-acting beta 2 agonists have a rapid and potent bronchodilating effect and represent the basis of treatment of acute asthma. Whatever the level of severity, the inhaled route is preferred because of its high efficacy/tolerance ratio. The doses and modes of administration depend on the severity of the airway obstruction, the site of management and the available devices. Long-acting beta 2 agonists are administered as regular treatment in moderately-severe to severe chaonic asthma in association to inhaled corticosteroids, mainly by the inhaled route whereas the oral route may be considered for the administration of prodrugs.