Molecular epidemiologic studies have shown that during respiratory syncytial virus (RSV) epidemics several subgroups of viruses cocircu-late. On the other hand, very similar strains can be found from widely separated countries at the same time. Nosocomial outbreaks make no exception because multiple sources of virus have also been found within one outbreak. Management of RSV infections has thus far varied largely but based on the recent reports some conclusions can be drawn. P-Sympathomimetics have been shown to be of benefit in the treatment of bronchiolitis whereas there is no data to support the use of systemic corticosteroids. Use of ribavirin cannot be recommended in common practice but it seems to have some beneficial effect in the high-risk patients. Mortality risk in the high-risk patients seems to have decreased in latest analyses compared with earlier reports. This has been attributed to improved supportive intensive care management and advances in cardiac surgery. Gammaglobulin has potential both in short-term prophylaxis and treatment of RSV infections. Development of a safe and effective vaccine is one of the main topics in RSV research. Despite some encouraging reports of active prophylaxis, such as use of recombinant fusion protein or temperature-sensitive mutants, we will probably not see a vaccine in clinical practice in the near future.