Inhaled drugs became of great interest in the treatment of childhood asthma. They must be adapted now to age and each form of the disease. The primarly interest of an organ therapy is to lead to a maximal efficacy by bringing locally an optimal quantity of drug without or with very few side effects. The choice of the device depends upon age which determines drug tolerance and quality of the inhalation technique. In infants and young children the use of nebulizers appears to be the most suitable technique; preschool children are capable to use metered-dose inhalers (MDI) with spacers; in older children the use of MDI, without spacers, or dry powder inhalers is allowed. During attacks of asthma, inhaled therapy appears to be effective in most cases using either B2 agonists alone in moderate forms, or B2 agonists associated with oral or parenteral corticoids in more severe forms. For the preventive treatment of asthma, in order to prevent attacks, some inhaled drugs also belong to a first line therapy against either allergy or on specific bronchial hyperreactivity: cromolyn or nedocromil are often used in mild to moderate forms (in association with oral anti-histamine drugs in some cases); in more severe forms we can start with a bronchodilator B2 agonist long-term treatment (associated with sustain-released theophyllin in some cases), except in infants before twelve or eighteen months of age; in the most severe forms of chronic asthma an anti-inflammatory long-term treatment with inhaled corticosteroids may be prescribed even in young children.