BACKGROUND: Rhinoviruses (RH) are responsible for acute respiratory illnesses, mainly in the upper respiratory tract. POPULATION AND METHODS: 3,152 children aged under 16 years, admitted to the Paediatrics department of the University Hospital Centre of Poitiers from January 1, 1993 to December 31, 1995 with ear, nose and throat (ENT) and/or respiratory symptoms were systematically investigated. One hundred and forty-five RH strains were isolated from nasopharyngeal secretions of 87 boys and 58 girls (mean age: 20.3 months). Among these, 92 (63.4%) were less than 1 year of age. Bacteriological investigations were done for 29 patients when a concomitant bacterial infection was suspected. RESULTS: RH infection rate was maximum before 1 year of age (median age: 6.5 months) and decreased with age. RH were isolated throughout the 3 years, with a first peak from February to April, and a second one in autumn. The main symptoms were sibilants (27.6%) and cough (24.1%). Sibilants were more frequently associated in children under 12 months of age (P = 0.01). Sometimes, ophthalmologic or digestive symptoms were present. Three children with respiratory distress were transferred to the reanimation ward. In addition, a RH strain was isolated from a child who died of sudden infant death. Thirty-four children (23.4%) were co-infected by one or several viruses; the most frequently detected were the respiratory syncytial virus (41.2%) and the adenoviruses (35.3%). Twenty-nine children were infected by two viruses and five by three. Associated bacterial infections were diagnosed in 23 children, especially conjunctivitis due to Haemophilus influenzae (21.7%). Among these children, eight had a multiple viral infection. CONCLUSION: RH have a limited pathogenicity but can be associated with serious illnesses among infants and children.