Respiratory syncytial virus (RSV) is one of the most common causes of lower respiratory tract infection in the developing world. Viral culture had low sensitivity for viral detection from PCR method lead to reduction in viral identification. In Iraq, little data are available for RSV detection, previous studies restricted on cell line culture and ELISA techniques. Hence, the current study aimed to investigate RSV-RNA in respiratory secretion with RT-PCR assay. One hundred children under 5 years with flu-like illness and negatively for influenza virus A and B types were tested for RSV.The real-time and conventional RT-PCR detection of RSV RNA were reported in 19% and 6%, respectively.The significant observed of RSV infection in children less than two years old. Moreover,the severity of disease was a significant increase in viral quantity from other RSV infection with mild disease.Sensitivity of conventional RT-PCR has not detected the positive cases in 68.4% of RSV infections at real-time RT-PCR assay in which the increasing of viral load were significant compared with those positive detectable in conventional RT-PCR. This study concludes a using multiplex PCR is important for diagnosis of RSV along with influenza virus, addition to human rhinovirus and the human met pneumonia virus as a potential infection of influenza like-illness which occur in the second most common cold pathogen.