This study investigated the prevalence of respiratory viruses, including respiratory syncytial virus (RSV), influenza virus types A and B (Flu A/B), parainfluenza virus (Para) 1-3, and adenovirus (Ad), in hospitalized children with acute lower respiratory tract infections (ALRIs). Immunofluorescence assays identified viral etiology in 412 patients younger than 16 years old. The overall viral isolation rate was 63.1% (260/412). The RSV was detected in 25.0%, Flu A/B in 19.4%, Para 1-3 in 14.6%, and Ad in 4.1% of the total sample. Multiple viruses were detected in 6.6% of the study population. Most viral infections occurred in the first 5 years of life, and the incidence of viral infection peaked during early spring and winter. Infection with Ad often resulted in the development of severe pneumonia in older children, and during the summer. The sequences of the isolated Ad hexons belonged to species B, and were closely related to the Gomen strain isolated in the United States in the 1950s. The study results will help determine the etiologic agents of ALRI in children and establish prevention and treatment programs.