Respiratory syncytial virus (RSV) is a common pathogen affecting the respiratory tract in infants. To date, there is limited data on RSV occurrence in Malaysia especially in the northeast of Peninsular Malaysia which is significantly affected by the rainy (monsoon) season. This study aimed to determine the prevalence, risk factors (the presence of a male sibling and older school-age siblings, parental education level, monthly income, chronic lung disease, immunocompromised, being a passive smoker, multipara, breastfeeding, prematurity, congenital heart disease, nursery attendance, and rainy season) as well as clinical manifestations of RSV in hospitalized infants and children with lower respiratory tract infection (LRTI). Patients' nasopharyngeal aspirates were tested for RSV antigen, questionnaires, and seasonal variations were used to assess RSV infection. Approximately 22.6% of children were infected with RSV; mean age 7.68 ± 5.45 months. The peak incidence of RSV as a causative agent for LRTI in infants was less than or equal to 1-year old (83%) with approximately 50.5% of the affected children in the younger age group (6 months amd below). RSV infection was significantly but independently associated with the rainy season (odds ratio, 3.307; 95% confidence interval, 1.443-3.688; P