This article is devoted to the investigation of experimental results of radiofrequency electromagnetic radiation effect on lipid peroxidation processes, Na + , K + -АТPase activity and antioxidant protective system enzyme activity in loach embryos. It was established that microwave radiation leads to intensification of lipid peroxidation processes and decrease of Na + , K + -pump activity during early embryogenesis. Under the effect of electromagnetic radiation, we have admitted an increase in superoxide dismutase activity; whereas the glutathione peroxidase activity decreased at each developmental stage. Catalase activity decreased at the I, IV, VI, VIII stages of blastomere division, however, it had opposite effect on the Х stage of division. Using two-factor analysis of variance, the estimation of microwave radiation effect (1; 5; 10; 20 min exposure) and developmental time (І, IV, VI, VIII, Х stages of blastomere division) on investigated rates during early embryogenesis has been provided. It has been shown that microwave radiation plays a significant role on free-radical process variability, Na + , K + -АТPase activity, the activity of superoxide dismutase and glutathione peroxidase and is one of the strongest factor (р≥0.999). Keywords: microwave radiation, loach embryos, lipid peroxidation, Na + , K + -ATPase, enzymes of the antioxidant defense system.