Bronchiolitis may be defined as a viral infection in infants before 2 years. The main features are obstruction of the small bronchi, with wheezing. In a study by Cherian (2), 114 infants with bronchiolitis have also feeding problems, in two thirds of case, intercostal and abdominal retraction in 90% of cases; fever is higher than 38 degrees 5C in only 30% of cases. The hospitalization rate is related to young age and low economic status. It is growing up for less 3 months infants (multiplicated by 7 for Black Payne). Acute bronchiolitis is quickly cured but recurrences are frequent chiefly in children living in day care centers. Relations between bronchiolitis and asthma are closed and the understanding is improved.