In a 5-year retrospective survey of respiratory syncytial virus (RSV) infections among hospitalized children, 1340 cases were identified of which, 98·4% were children <5 years old with a male:female ratio of 1·5:1. Most cases occurred from April to September showing a significant positive correlation with temperature and relative humidity. Community-acquired infections accounted for 92·5% of the cases with a mean hospital stay of 5 days. The estimated annual incidence of RSV infection requiring hospitalization was 2·5/1000 children <5 years old with a mortality of 0·15% among hospitalized cases. On average, 248 children were admitted each year to the 1400-bed acute regional hospital accounting for an expenditure of HK $1.94 (∼US $0.25) million for hospitalization costs which equates to an annual cost in excess of HK $6.67 (∼US $0.86) million for the whole of Hong Kong. An RSV vaccine should be a priority.