Antifungal activity of micelial fungus metabolites (of genera Aspergillus, Penicillium, Fusarium, Stachybotris, Cladosporium, Alternaria, Gliocladium, Paecilomyces, Trichoderma etc.) was determined. It was shown that antifungal activity of some micromycetes is due to the formation of substances inhibiting sterols biosynthesis in eucaryote cells. Inhibitors of enzymes of sterols biosynthesis were isolated and their activity was investigated. It was shown, that isolated fungus inhibitors of sterols biosynthesis inhibited the growth of test-organism Rhodotorula rubra and decreased ergosterin level in yeast cells. The qualitative content of yeast cell sterols was not changed in the presence of fungus inhibitors.