Among 873 children hospitalized with confirmed respiratory viral infections, 492 suffered from bronchopulmonary obstruction. Respiratory syncytial virus infections were dominant among the patients with bronchopulmonary obstruction (80%). The majority of patients with rhinovirus infections suffered from bronchopulmonary obstruction (57%). Two main groups of children at risk from developing bronchopulmonary obstruction during respiratory virus infections were found: 1) infants, suffering from bronchiolitis, mainly due to respiratory syncytial virus, and 2) children of all ages with bronchial asthma, among whom acute attacks were precipitated by virus infections, mainly rhinovirus and respiratory syncytial virus infections. The pathogenesis of bronchopulmonary obstruction during respiratory virus infections is discussed.