RNA interference (RNAi) is the process by which double-stranded RNA directs sequence-specific degradation of homologous mRNA. Short interfering RNAs (siRNAs) are the mediators of RNAi and represent powerful tools to silence gene expression in mammalian cells including genes of viral origin. In this study, we applied siRNAs targeting the VP7 gene of African horse sickness virus (AHSV) that encodes a structural protein required for stable capsid assembly. Using a VP7 expression reporter plasmid and an in vitro model of infection, we show that synthetic siRNA molecules corresponding to the AHSV VP7 gene silenced effectively VP7 protein and mRNA expression, and decreased production of infectious virus particles as evidenced by a reduction in the progeny virion titres when compared to control cells. This work establishes RNAi as a genetic tool for the study of AHSV and offers new possibilities for the analysis of viral genes important for AHSV physiology.