Short-term impact of the low intensity electromagnetic radiation on in vitro growing Daphnia magna Straus embryos was studied. Embryos were exposed to laser radiation (633 nm, 0.05 mW/cm²) and ultraviolet radiation (365 nm, 0.16 mW/cm²) separately as well as in sequential combinations. It was shown that short-term impact of the laser radiation on early life stages of D. magna led to produce well-grown offspring. Action of the ultraviolet radiation led to disturbance of a general correlation between daphnids sizes and number of produced offspring. The prior exposure of embryos to laser radiation, before the ultraviolet radiation action, did not lead to such changes.