There is little French data on the characteristics of infants hospitalized for bronchiolitis. An analysis of data from the Medical Information Systems Program (PMSI) was conducted to describe cases of bronchiolitis requiring hospitalization. An analysis was conducted of all hospital stays for infants under 1 year of age in 2009 for whom a diagnosis of acute bronchiolitis had been recorded in the PMSI. Factors associated with death during hospitalization were studied using logistic regression. The hospitalization rate was 35.8 per 1,000 infants under 1 year of age. Twenty-two infants died, representing a case-fatality rate of 0.08% for all cases and 0.56% for those hospitalized in acute care units. Mortality among all infants under 1 year of age was 2.6 per 100,000. Factors associated with death were the presence of bronchopulmonary dysplasia, hospitalization in an acute care unit, and the use of mechanical ventilation. This study quantified the hospitalization rate and case-fatality rate at the national level using a medical-administrative database. The results are comparable to those in the international literature. Prospective analyses are needed to better identify high-risk cases and improve their management. (R.A.)