Background: Respiratory syncytial virus (RSV) is one of the main viral pathogens causing acute respiratory infections in children under 5 years of age, but has seldom been studied in Central African Republic (CAF). Methods: Taking advantage of the national influenza surveillance network in CAF, a total of 3903 children under 5 years matching the influenza-like illness (ILI, 68.5%) or severe acute respiratory infection (SARI, 31.5%) case definitions were recruited from January 2015 to December 2018 to determine annual RSV prevalence, seasonality and disease severity as well as to characterise RSV strains. The presence of RSV viral RNA in nasopharyngeal samples was assessed by RT-PCR, followed by RSV-A and –B typing and Sanger sequencing. Results: RSV incidence was significantly higher in infants < 6 months (13.4%), in hospitalized children (13.3% vs 5.5%) and in male patients (9.5% vs 6.4%). An overall prevalence of RSV of 8.0% in the period of 2015-2018 was shown, with significant annual (6.4%-10.6%) and seasonal (12.7% in rainy season vs 3.0% in dry season) fluctuations. While RSV seasons in 2015, 2016 and 2018 were relatively similar, 2017 showed deviations from the overall patterns with significantly higher RSV incidence and peak incidence 3-5 months earlier. Concomitant circulation of RSV-A and RSV-B with an alternating predominance of RSV-A and RSV-B strains and temporal RSV-A genotype replacement from NA1 to ON1 were observed. Conclusion: This study represents the first in-depth epidemiological analysis of RSV in CAF and provides first insights into RSV burden, genetic diversity and seasonality in the country.