Foot-and-mouth disease virus (FMDV) is a highly contagious pathogen of cloven-hoofed mammals and one of the biggest concerns for veterinary authorities. The control measures to be applied in case of an outbreak vary in function of the disease-free or disease-enzootic status. Vaccination depends on the prior identification of the involved viral serotype and subtype, it confers an immunity limited to 6 months and it requires between 4 to 7 days to trigger the immune response (i.e. immunity-gap). The use of anti-FMD drugs has been discussed as an alternative or supplementary method to be used in previously FMD-free countries/zones. Such an antiviral treatment could protect against the viral dissemination to fill the gap between vaccination and the rise of a protective immunity. Apart from broad spectrum antiviral agents, such as ribavirin, specific anti-FMDV molecules have been identified in vitro, but none of them has been used in clinical studies involving ruminants or pigs. Next to the anti-FMDV activity, the absence of toxicity and the withdrawal period influencing the food safety, the cost of the treatment would be another important parameter influencing the potential use of an antiviral agent in the control of a FMD outbreak. The aim of this study was to assess the economic impact of using an antiviral in the control of a FMD epizootic in southern Belgium (Walloon Region). This work was based on the results of previous investigations concerning the epidemiological and economic data of a FMD outbreak in Southern Belgium. In the considered scenario, the epizootic was caused by the introduction of an infected cow (during the incubation time) in a beef cattle farm during winter. During the two weeks between the brood cow introduction and the official declaration of the outbreak, animal movements occurred between other beef cattle farms. The economic effects of the epidemic were evaluated taking into account the air-borne transmission of FMDV, the occurrence of animal movements (two scenarios were considered, with a minimum of 2 and a maximum of 17 movements), the presence of bovine and small ruminant farms, as well as pig farms in the protection and surveillance zones around the initial and secondary outbreaks. The wild fauna was not involved in the epidemic. In order to integrate in the above scenario the application of an antiviral agent in the control of the disease, it was assumed that the efficacy of the anti-FMDV drug was proven by reducing viral excretion in infected animals as well as by preventing the infection in animals at risk. Two hypothetical prices were used to introduce in the model the costs related to the administration of the antiviral drug (5€ and 10€ per dose). Furthermore, different strategies of control could be envisaged, such as the administration of the drug to both domestic ruminants and pigs, or depending on the epidemiological role of these species in the FMD transmission and their density in the territory, the administration of the drug to only one of them. Other scenarios could be characterized by the use of the antiviral in the control of the epizootic within the protection and surveillance zones or in only one of them. The costs associated with the use of antivirals in the different proposed scenarios are compared to the costs and socio-economic losses associated with the FMD outbreak and the implementation of control measures.