Bronchiolitis represents a heavy burden of disease in children under 2 years of age in our society due to the high infectivity of the Respiratory Syncytial Virus [RSV] and the vulnerability of the youngest children.The objective of this retrospective epidemiological study was to show the burden of severe bronchiolitis in Spain through population-based estimates of hospitalizations due to bronchiolitis in children up to 24 months old during a 6-year period (2012-2017).A total of 100,115 cases of bronchiolitis required hospitalization in Spain from 2012 to 2017. Most cases of bronchiolitis that required hospitalization were in infants under 3 months of age. The hospitalization rate for bronchiolitis for children under 1 year of age was 3,838.27 per 100,000 healthy children. During the 6-year study period, a total of 82 deaths due to bronchiolitis were reported among hospitalized infants. Among these deaths, more than 50% were in patients younger than 3 months of age. The annual average cost to the National Health Care System was €58 M, with a mean hospitalization cost of €3,512 per case.