Experiment results of the study of extremely high frequency millimeter waves (EHF) of 60.12; 53.33 and 42.19 GHz effect on biomass accumulation and biosynthetic activity of Saccharomyces cerevisiae CNMN-Y-20 and Saccharomyces cerevisiae CNMN-Y-18 yeast strains - polysaccharides producers deposited in National Collection of Nonpathogenic Microorganims of Institute of Microbiology and Biotechnology of Academy of Sciences of Moldova have been revealed. Duration of treatment of yeast strains in carried out study constituted 10, 20, 30 minutes. Research has demonstrated the efficiency of extremely high frequency electromagnetic radiation for stimulation of biosynthetic processes at yeasts manifested in the increase of bioactive substances content while the stimulation or maintaining at the same level of biomass production. The irradiation of yeast strains with millimetric waves contributed to the increasing of carbohydrates with 29-43.5%, β-glucans with 17.4-25.7%, mannans with 11.2-21% and protein content with 26.9-49.9 % as well as to the increasing of catalase activity with 34.5-69.2% compared to the control in dependence on strain, used frequency and duration of irradiation.