Acute bronchiolitis (AB) is a frequent cause of hospitalization among children and its main etiological agent is respiratory syncytial virus (RSV). It occurs epidemically during autumn and winter. Some populations of children such as premature newborns, infants with congenital heart disease and those with chronic lung disease, immunocompromised, undernourished, among others, present increased morbidity and mortality risk. The virus multiplies in epithelial ciliated cells while inflammation and cellular debris cause obstruction of the airways, hyperinflation, atelectasis, and wheezing and gas exchange imbalance. Definitive evidence still does not exist about treatment of this disease, Treatment includes oxygen therapy, hydration, inhaled beta-2 agonists, racemic epinephrine, recombinant DNase and respirotherapy, among others. Prophylactic measures include administration of monoclonal antibodies. The majority of children with AB, independent of disease severity, recover without sequels. The natural course of this disease usually varies, from seven to ten days ,however some children may not recover for weeks.