We study the clinical, management and outcome differences between respiratory syncytial virus (RSV) positive and negative bronchiolitis. A retrospective review of the medical records of children ≤ 2 years of age with acute bronchiolitis between January 1995 and December 2006 was done. There were 2,384 patients hospitalized for acute bronchiolitis, and 1,495 (62.7%) were RSV infections. Overall, hospitalization rate was 55/1,000 admissions. Mortality occurred in 0.08% of cases. Bronchiolitis due to RSV was more frequent from November to March (97%). RSV bronchiolitis had longer hospital stays (6 vs. 5 days, P<0.0001), higher risk of intensive care unit (ICU) admission (OR 2.7; 95%CI 1.87-3.9) and more oxygen use (OR 2.2; 95%CI 1.8-2.6). Infants < 2 months had longer median hospital stay (6 vs. 5 days, P <0.0001) and higher risk of ICU admission (OR 3.4; 95%CI 2.5-4.6). Prematures of < 32 gestational weeks, congenital heart disease, and atelectasis/condensation were the main risk factors for ICU admission in both RSV and non-RSV bronchiolitis. The introduction of palivizumab in prematures diminished hospitalization for RSV bronchiolitis, oxygen need, length of hospital stay and mechanical ventilation. In conclusion, this study supports that RSV bronchiolitis seems to be a more severe disease than that caused by other viruses.