BACKGROUND: Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections and hospitalization in infants. Palivizumab is currently the only available agent for prevention of RSV infection in highrisk infants. This high-cost injectable requires monthly dosing during the RSV season. Compliance with the injection schedule is important in the prevention of RSV infection and respiratory complications. Managed care organizations have an interest in the relationship between compliance with the palivizumab dosing schedule and respiratory-related medical outcomes such as emergency room (ER) visits, physician office visits, and hospitalizations.