Asthma is a chronic lung condition in children, and often requires hospitalization for acute exacerbations. Azithromycin has been used successfully in other chronic lung diseases, including cystic fibrosis. Despite limited clinical evidence, some pediatricians use azithromycin in children hospitalized with asthma, citing either treatment of atypical pathogens or its proposed anti-inflammatory properties. We propose a clinical trial to determine if azithromycin will shorten length of stay in children hospitalized with acute asthma exacerabations.