OBJECTIVES: Age-specific economic burden of RSV hospitalizations is poorly documented. We assessed national estimates of age-specific economic burden of RSV hospitalizations in the US. METHODS: A retrospective cohort study using the HCUP NIS between January 2009 and December 2013 was conducted. NIS includes discharge data on 20% of all US hospitalizations. Hospital admissions for RSV were identified using records with a principal ICD-9 diagnosis code of 466.11 or 480.1. We analyzed hospitalizations in 5 age categories (<1, 1–4, 5–49, 50–64, and >65yrs). Total inpatient costs (converting charges to cost using cost-to-charge ratio), hospital length of stay (LOS), and mortality during the inpatient visit were assessed. RESULTS: A total of 75,427 RSV hospitalizations were identified. The highest hospitalizations were in patients <1yr (72%) followed by 1-4yr age group (25.3%). Mean LOS was highest in the 49-64yr age group (8.3 days, SE 0.6) and lowest in the 1-4yr age group (3.0 days, SE 0.03). Correspondingly, mean cost per stay was highest in the 49-64yr age group ($29,777.00, SE 4518.0) and lowest in the 1-4yr age group ($5,639.97, SE 201.6). in <1yr and 1-4yr age groups. Records with a presence of asthma or COPD had 27% and 35% higher mean cost per stay, respectively. Based on weighted frequency, total national hospitalization cost of RSV admissions between 2009 and 2013 was $2.3 billion of which $1.5 billion (67.4%) was attributable to patients of age <1yr. Inpatient mortality was highest (5.1%) in the 49-64yr age group. CONCLUSIONS: Economic burden of RSV varies dramatically by age groups. RSV hospitalizations are highest in the children <5yrs and accounts for 90% of the total national hospitalization costs of RSV. Elderly patients, though low in numbers, have higher mortality, LOS, and cost per stay compared to young children.