The effectiveness of bacteria of the genera Sphingomonas and Bacillus, and yeasts of the genera Cryptococcus, Rhodotorula, and Saccharomyces as biological control agents against pathogens colonizing winter wheat, was tested in laboratory conditions. All of the tested yeast isolates had an inhibitory effect on the development of F. sporotrichioides colonies. Under the same conditions, the Sphingomonas S 11 isolate was antagonistic against F. avenaceum, F. culmorum, F. tricinctum, and F. graminearum. The seedlings of winter wheat cv. Sumai treated with a suspension of Sphingomonas S 11 bacteria and inoculated with F. culmorum demonstrated significantly fewer infection symptoms than unprotected seedlings that were inoculated with the above-mentioned pathogen.