Objectives: Bronchiolitis is the most common disease of the lower respiratory tract in the first year of life. Treatment is controversial, with studies giving conflicting views on the benefits of bronchodilators and steroids. The objectives of this study were 1) to characterize the management of bronchiolitis in pediatric emergency departments (PEDs) in Canada, 2) to determine patient outcomes following emergency department (ED) visits, and 3) to provide descriptive data regarding bronchiolitis symptoms and family/ personal medical history of these patients. Methods: A prospective consecutive cohort of children with bronchiolitis presenting to seven Canadian PEDs was enrolled during a seven-to-21-day period. Standardized interviews with parents provided data regarding symptoms, previous treatment, and past history. Charts were reviewed for treatment, investigations, and disposition. Telephone follow-up at two to three weeks collected information regarding duration of illness and return visits. Results: Two hundred thirty-seven (91%) of 260 eligible patients were enrolled. One hundred eighty-nine patients (80%) had both an interview and chart review, and 48 (20%) had only chart reviews; follow-up was completed for 163 (69%) patients. One hundred fifteen (63%) had seen their primary care provider during their illness prior to the ED visit. Seventy-three percent of patients (range per site 59-100%) were treated in the ED with bronchodilators (usually salbutamol or epinephrine) and 5% (range per site 0-14%) with oral steroids. Twenty-four percent (58/237) were prescribed bronchodilators on discharge, 3% (7/237) inhaled steroids, and 2% (5/237) oral steroids. Chi-square tests indicated significant practice variation by site in ED bronchodilator use (p < 0.001) and bronchodilator use at discharge (p = 0.0003). Admission rate was 31% (range by site 22-43%), 17% of patients had more than one ED visit, and 1% were admitted more than once. Admission rates were increased in younger children, children with comorbidities, and children with lower oxygen saturation. Viral studies were obtained in 53%, with 76% of these positive for respiratory syncytial virus (RSV). Median duration of cough was 12 days, poor sleeping and irritability eight days, and wheeze and poor feeding seven days. Conclusions: This study prospectively describes the treatment of bronchiolitis in the pediatric ED. The findings are consistent with the literature regarding the reported use of bronchodilators; however, use of steroids was found to be much lower than reported in other studies. Bronchodilator use in the ED and at discharge varied significantly by site. The results capture variation in treatment practices in Canadian PEDs, which may be the result of discordant randomized controlled trial evidence. Further research is needed to establish best practices.