AimsThe present study was conducted to evaluate the antagonistic effect of BacillusvelezensisNRRL B-23189 towards Penicillium roqueforti s.s. and Penicillium paneum (designated together as P.roqueforti s.l.) in silage conditions. Methods and ResultsCorn silage conditions were simulated invitro, and the impact of B.velezensis culture supernatant or cell suspension on P.roqueforti s.l. growth and roquefortine C production was evaluated. The antagonism was promising, but growth of B.velezensis in corn silage infusion was poor. Additionally, an invivo experiment was carried out with mini-silos containing a mixture of perennial ryegrass and white clover inoculated with P.roquefortis.l. The applied B.velezensis cell suspension was unsuccessful in reducing P.roquefortis.l. numbers, but did not compromise the silage acidification. ConclusionsAlthough the antagonism observed invitro was promising, the applied B.velezensis cell suspension could not live up to the expectations invivo. Significance and Impact of the StudyTo our knowledge, the present study is the first one evaluating the antagonistic properties of B.velezensis towards toxigenic moulds in silage conditions, offering a good base for further research.