Background: Acquired infections in hospitalized elderly people are a growing concern. In long-term care facilities with multiple staff and visitor contacts, virus outbreaks are a common challenge for infection prevention teams. Although several studies have reported nosocomial RSV outbreaks in long term care facilities, molecular epidemiology data are scarce. Methods: RSV RNA was detected in respiratory samples from 19 patients in a long-term care hospital for elderly in Paris in March 2019 over a 3 weeks period. Genotyping was performed using nucleotide sequencing. Sociodemographic and clinical characteristics of cases part of a unique cluster, were retrospectively reviewed. Results: Molecular investigation of theses RSV cases, revealed a unique cluster of 12 nosocomial cases in 2 adjacent wards. Mean age of these outbreak's cases was 89. All patients had underlying medical conditions. Seven exhibited lower respiratory symptoms and three experienced decompensation of underlying chronic heart condition. Two patients died. Conclusions: This case report highlights the importance of RSV in causing substantial disease in elderly in case of nosocomial outbreak and the contributions of molecular epidemiology in investigation and management of such outbreak.