Neutron activation analysis of the Pleurotus ostreatus showed that adding of solid solution of ZrO2-Y2O3 hydroxide and oxide (3 mol % Y2O3) nanoparticles of size 4 and 9 nm at a concentration of 0.2 weight percent in a nutrient medium (Czapek) alters the character of physiological processes in the biological tissues of the mushrooms. This is manifested in the form of a significant change in morphological and physiological characteristics of the mushrooms and the elemental composition of the dry biomass. In particular, it is shown that the intercalation of nanoparticles into the tissues of the mushrooms leads to an increase of 1.3-1.4 times (more than 2.6 g/dm3) of biomass accumulation (industrial strain HK 35) and decrease of 1.7-1.8 times (below 1.7-2.5 mg/mm3) of concentrations of extracellular proteins into the culture fluid at a substantially constant value of the acidity. It is shown that the addition of ZrO2+3 mol % Y2O3 nanoparticles of sizes 4 or 9 nm into tissue of mushroom at step of the mother mycelium in very small concentrations can alter effectively the chemical composition of the substances produced by the cells and consequently, its physiological activity. It is shown that the use of low concentrations of ZrO2 nanoparticles allow to increase the yield and resistance of crops to diseases up to 1.2-1.5 times, as well as in the long term can be used in biomedical technologies for the treatment of cancer diseases.