Asthma is a leading cause of morbidity and mortality among children worldwide, as is respiratory syncytial virus (RSV). This report reviews controlled retrospective and prospective studies conducted to investigate whether there is an association between RSV bronchiolitis in infancy and subsequent development of reactive airway disease or allergic sensitization. Findings indicate that such a link to bronchial obstructive symptoms does exist and is strongest for children who experienced severe RSV illness that requires hospitalization. However, it is not yet clear what roles genetic predisposition and environmental or other risk factors may play in the interaction between RSV bronchiolitis and reactive airway disease or allergic sensitization. Randomized, prospective studies utilizing an intervention against RSV, such as a passive immunoprophylactic agent, may determine whether preventing RSV bronchiolitis reduces the incidence of asthma.