The epidemiology, etiology and pathophysiology, clinical presentation and diagnosis, and drug therapy of asthma in children are reviewed. Recent advances in drug therapy have, for unknown reasons, been accompanied by an increase in the morbidity and mortality associated with childhood asthma. The cause of asthma is not precisely understood, but an inflammatory process and hyperactivity of airways are common findings in the disease. Asthma in children can be classified as intermittent, chronic, or indeterminate; a severe, prolonged episode not relieved by usual treatment is called status asthmaticus. The hallmark symptoms of asthma are coughing, dyspnea, and wheezing. Beta-adrenergic agonists can be used orally for diagnostic purposes or for nocturnal asthma; i.v. or s.c. for emergency treatment; or by inhalation for relief of acute asthmatic episodes. Experience with anticholinergics in children is limited, and these agents should be used only when other options have failed. Inhalation of cromolyn sodium is very safe and is useful for the prophylactic treatment of mild to moderate asthma. Corticosteroids, which are used both for acute asthmatic episodes and for long-term treatment, can be given orally, i.v., or by inhalation. Theophylline is used for prophylactic therapy in children with chronic asthma. Selection of a drug regimen is based on knowledge of efficacy, pharmacokinetics, compliance, and toxicity. The treatment of asthma in children requires consideration of drug properties in young patients. Drugs used to treat childhood asthma include beta agonists, anticholinergics, cromolyn sodium, corticosteroids, and theophylline.