Yeast of different taxonomic groups isolated from the organism of long-livers of Abkhazia have been studied for their antagonistic activity relative to the conditionally pathogenic and pathogenic bacteria and for the presence of the killer factor. It is shown that representatives of ten species of fungi are antagonists of the studied bacteria, the strains of Saccharomyces cerevisiae being the most active antagonists. The presence of the killer factor is found in representatives of five species o the yeast. It is supposed that the antagonistic activity relative to the bacteria and the killer activity in the yeast are due to substances of different chemical nature.