The ultrastructural organization of loach embryo cells (Misgurnus fossilis L) at the stage of the first and the tenth embryo divisions was investigated in the control and under the influence of low intensity helium-neon laser irradiation of 5 min exposure. The effect of laser irradiation led to ultrastructural changes in cell organelles, increasing the number and size of mitochondria, and as a result their shape changes. Under the influence of laser irradiation, the activation of cellular digestion processes took place, the number of vacuoles and lysosomes increased. The results explain the possible mechanism laser irradiation impact at the cellular level.