en Virology Virology Original Research Original Research <p> <strong> Background </strong>:Respiratory viruses are the leading cause of respiratory tract infections among children and are responsible for causing morbidity and mortality worldwide. This study was performed to detect viruses in children with respiratory infections and describe their epidemiology and clinical characteristics. </p><p> <strong> Methods </strong>: In this descriptive cross sectional study, throat swabs and wash specimens from 202 children younger than six years of age with diagnosis of a respiratory tract infection from a total of 897 specimens were evaluated using multiplex PCR method. </p><p> <strong> Results </strong>: Respiratory viruses were detected in 92 children: respiratory synsytial virus, 16.8% influenza virus, 5.4% parainfluenza virus, 8.4% adenovirus, 14.4% and human metapneumo virus 0.49% with male predominance and higher distribution in children younger than 1 year of age with preference in the cold months of year. The clinical presentations of all detected viruses were almost similar. </p><p> <strong> Conclusion </strong>: In the present study, nine different respiratory viruses were detected. RSV causes the great majority of respiratory virus infections in children. There was no significant difference in epidemiologic patterns of these viruses in comparison to other studies. </p><p>  </p> Children, Epidemiology, Iran, Respiratory viruses. 659 664 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-734&slc_lang=en&sid=1 Somayeh Shatizadeh shatizadeh@razi.tums.ac.ir 200319475328460013337 200319475328460013337 No Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Jila Yavarian yavarian@sina.tums.ac.ir 200319475328460013338 200319475328460013338 No Department of virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Farhad Rezaie rezaie@tums.ac.ir 200319475328460013339 200319475328460013339 No Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Mahmood Mahmoodi mahmoodim@tums.ac.ir 200319475328460013340 200319475328460013340 No Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Maryam Naseri mn_naseri@yahoo.com 200319475328460013341 200319475328460013341 No Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Talat Mokhtari Azad mokhtari@sina.tums.ac.ir 200319475328460013342 200319475328460013342 Yes Department of virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.