Respiratory syncytial virus (RSV) infects nearly all children by age 2 years, and it causes considerable illness and death in certain high-risk pediatric populations. Historically, treatment for RSV has been symptomatic, and developing a safe and effective vaccine has been a challenge. Therefore, research efforts have turned to passive immunization as the best option to control RSV. Palivizumab, a genetically engineered humanized monoclonal antibody, has been shown to reduce RSV-related hospitalizations significantly, with few adverse effects. It was approved for use in high-risk children in the USA in 1998 and in Europe in 1999; it is now approved for use in more than 45 countries. The efficacy and safety of palivizumab continue to be supported by both clinical trial and outcomes data.