Introduction - Influenza can be a nosocomial infection. Hospital outbreaks have been reported, but rarely in pediatric wards. A prospective study was conducted at Edouard Herriot Hospital in Lyon to describe cases of nosocomial influenza and any potential transmission within the hospital. Methods - Over two winters from 2005 to 2007, hospitalized children and healthcare staff presenting with influenza-like illness were included in this study with their consent. For each case, medical data were collected and a nasal swab was taken to establish the virological diagnosis. The case’s daily contacts were also documented to describe potential in-hospital transmissions. Results - The study identified 595 cases of influenza-like illness, including 553 children and 42 healthcare workers. Among those included, 90 children and 5 healthcare workers had confirmed influenza. Nosocomial influenza cases were observed each year (1 child and 4 healthcare workers); potential transmissions were identified only during the second season. Conclusion - The occurrence of nosocomial transmission highlights the importance of vaccination and hygiene precautions. In pediatric wards, the low number of nosocomial influenza cases suggests that these precautions are being well followed (R.A.)