OBJECTIVE: To study the virus spectrum of severe community-acquired pneumonia (CAP) and risk factors for the disease in children. METHODS: Respiratory secretion specimens were collected from 1096 children hospitalized with CAP from June 2007 to November 2008, including 100 cases of severe CAP. Respiratory viruses were detected by PCR, nest-PCR or RT-PCR. Clinical data on the children were analyzed by univariate and multivariate logistic regression analysis for examining risk factors for severe CAP. RESULTS: Viral pathogens were isolated from 82 (82%) of the 100 cases with severe CAP. RSV was the most common (37%), followed by HBoV (25%) and HRV (18%). Mixed infection was noted in 32 cases (32%). The presence of underlying diseases (OR=6.623, P<0.01) and RSV infection (OR=1.672, P<0.05) were risk factors for severe CAP in children, while age was a protective factor (OR=0.475, P<0.01). CONCLUSIONS: RSV is the most frequent viral pathogen in children with severe CAP. The presence of underlying diseases and RSV infection may be risk factors for severe CAP, while age is a protective factor.