The qualitative and quantitative composition of water-soluble vitamins B in Saccharomyces yeasts cultivated on various nutrient media was studied by high-performance liquid chromatography. New strains of Saccharomyces oviformis Y-2635 and Saccharomyces vini F-5 yeasts grown in the nutrient medium with geothermal water differed in great biological value due to high intracellular concentrations of riboflavin, thiamine, nicotinic acid, and folic acid.