Treatment of respiratory syncytial virus (RSV) in infants with bronchiolitis is complicated because of the multifactorial nature of this infection. The signs and symptoms of RSV result from a combination of direct viral cytopathic effects, host inflammatory responses that lead to airway obstruction and bronchoconstriction. It is logical that therapies targeting just one of these processes might be minimally effective, at best. Thus an important goal is to identify patients at risk and intervene to prevent disease, whenever possible. Once disease has been identified, the clinician must decide whether antiviral therapy is appropriate. Familiarity with typical viral load dynamics during the course of a lower respiratory tract infection can assist in the therapeutic decision process. For example in a patient who has had airway obstruction and other respiratory symptoms for >3 days, viral load has already peaked. Clearly this pattern has important implications for antiviral therapies.Preventive strategies include educating parents and family about hand washing, cleaning environmental surfaces, isolating infants and children with infection and avoiding crowded places such as busy day-care centers. High risk patients, who meet the American Academy of Pediatrics criteria for RSV prophylaxis, may be candidates for passive prophylaxis.