Background: Respiratory Syncytial Virus (RSV) is the leading cause of acute lower respiratory infection (ALRI) in children. We aimed to describe the clinical-epidemiological pattern and risk factors for mortality associated with RSV infection. Methods: A prospective, cross-sectional study of ALRI in children admitted to the Children's Hospital among 2000-2017. Viral diagnosis was made by fluorescent antibody techniques or real time-PCR. We compared clinical-epidemiological characteristics of RSV infection in non-fatal versus fatal cases. Multiple logistic regression was used to identify independent predictors of mortality. Results: Of a total 15,451 patients with ALRI, 13,033 were tested for respiratory viruses and 5831 (45%) were positive: RSV 81.3% (4738), influenza 7.6% (440), parainfluenza 6.9% (402) and adenovirus 4.3% (251). RSV had a seasonal epidemic pattern coinciding with months of lowest average temperature. RSV cases show a case fatality rate of 1.7% (82/4687). Fatal cases had a higher proportion of: prematurity (p<0.01), perinatal respiratory history (p<0.01), malnourishment (p<0.01), congenital heart disease (p<0.01), chronic neurological disease (p<0.01) and pneumonia at clinical presentation (p=0.014). No significant difference between genders was observed. Most deaths occurred among children who had complications: respiratory distress (80.5%), nosocomial infections (45.7%), sepsis (31.7%) and atelectasis (13.4%). Independent predictors of RSV mortality were: moderate to severe malnourishment, OR 3.69 (95% CI 1.98-6.87) p< 0.0001, chronic neurological disease, OR 4.14 (95% CI 2.12-8.08) p< 0.0001, congenital heart disease, OR 4.18 (95% CI 2.39-7.32) p< 0.0001 and the age less than 6 months, OR 1.99 (95%CI 1.24-3.18) p=0.004.