Respiratory syncytial virus (RSV) infection was searched for in 65 children between 2 months and 2 years of age hospitalized with the presumptive diagnosis of acute bronchiolitis, and in 35 children aged 6 months to 8 years with upper respiratory tract symptoms, by direct fluorescent antibody (DFA) test and cell culture. RSV infection was detected in 29.2% of the first and in 11.4% of the second group. The overall positivity rate was 23%. The sensitivity and the specificity of the commercially available DFA test in comparison with cell culture were 81.8% and 92.5%, respectively.