The epidemiology of RSV infection was investigated in 271 children aged less than 2 years admitted to the Zarqa Government Hospital, Jordan with bronchiolitis or bronchopneumonia. Nasopharyngeal washings were cultured and RSV antigen was detected by the direct immunofluorescence technique. Of the 271 specimens, 69 (25.46%) were positive for RSV, representing 50.36% of the respiratory viruses. All RSV isolates were typed as subgroup A by monoclonal antibody and confirmed by RT-PCR. RSV was prevalent in the hospitalised children in the coldest months of the year. The epidemics began in January or February, peaked in spring and then disappeared in summer. This study supports the idea that RSV subgroup A is a major contributor to winter outbreaks of respiratory tract disease in children, and health care workers in Jordan should consider the diagnosis during January-May each year.