In this paper the relationships between selected strains of G. candidum yeasts originating from different sources (malt, mould cheese) and toxigenic Fusarium species, which are common in com seeds, have been examined. The three methods: biotic test, spot test and diffusion test were used for interaction between the microorganisms. Tested yeasts were grown on different media: PDA, ME, Czapek and YEG. It was proved that the antagonistic activity depends on the strain of yeasts and moulds. Three species of fungi F. graminearum, F. sporotrichoides and F. poae showed higher sensitivity to the yeasts presence, two other species F. avenaceum and F. culmorum were less sensitive. The process of slowing down the growth of the tested moulds was mainly the result of the competition for living space.