BACKGROUND: We sought to know more about how 14 common respiratory viruses manifest clinically, and to identify risk factors for specific virus-induced acute respiratory tract infections (ARTIs) in children younger than 3 years old and for wheezing at 36-month follow-up. METHODS: We retrospectively studied the clinical records for 273 full-term children (median age, 2.9 months; range, 0.26-39; boys, 61.2%) hospitalized for ARTIs, whose nasopharyngeal specimen tested positive for a respiratory virus and 101 children with no history of respiratory diseases (median age, 8 months; range, 0.5-36.5; boys, 58.4%). At 12, 24 and 36 months after children\'s discharge, all parents were interviewed by telephone with a structured questionnaire on wheezing episodes. RESULTS: The most frequently detected viruses were respiratory syncytial virus in bronchiolitis, human rhinovirus in pneumonia and human bocavirus in wheezing. Multivariate analysis identified, as risk factors for virus-induced ARTIs, the presence of siblings [odds ratio (OR): 3.0 (95% confidence interval [CI]: 1.8-5.2)], smoking cohabitants (OR: 2.3 (95% CI: 2-4.2)] and breastfeeding lasting less than 3 months [OR: 0.5 (95% CI: 0.3-0.9)]. The major risk factor for respiratory syncytial virus-induced ARTIs was exposure to tobacco smoke [OR: 1.8 (95% CI: 1.1-3.2)]. Risk factors for human rhinovirus-induced ARTIs were attending day-care [OR: 5.0 (95% CI: 2.3-10.6)] and high eosinophil blood counts [OR: 2.6 (95% CI: 1.2-5.7)]. The leading risk factor for recurrent wheezing was exposure to tobacco smoke [OR: 2.5 (95% CI: 1.1-15.6)]. CONCLUSIONS: Each respiratory virus leads to a specific clinical manifestation. Avoiding exposing children to tobacco smoke might restrict viral spread from sick parents and siblings to younger children, prevent severe respiratory diseases, and possibly limit sequelae.