Respiratory syncytial virus (RSV) is one of the major respiratory tract viral pathogens throughout the world, causing acute lower respiratory infections among infants and young children. The present study was undertaken to compare between nested RT-PCR and viral culture methods for the detection of RSV infection in infants. This study included 107 pediatric patients admitted to Cairo University Children Hospitals with lower respiratory tract infections. RSV was isolated in 81 nasopharyngeal aspirates by viral cultures and identified in 88 samples by nested RT-PCR. In 7 samples RSV was identified by nested RT-PCR alone. In conclusion PCR appears to be more sensitive than viral cultures for detection of RSV in clinical samples.