Effects of ultrasound on the sex differentiation and embryonic mortality was tested on the set of 772 eggs of the Rhode Island Red and Hampshire strain chicken. In control groups, embryos were not exposed to ultrasound during incubation. In experimental groups, chicken embryos were exposed to ultrasound generated by the transducer oscillating at the frequency of 30 kHz with the power of 60 W. Embryonic mortality was significantly higher in the experimental groups exposed to ultrasound. Pathogenic effects of ultrasound were more pronounced in embryos with already developed allantochorionic blood circulation. It can be assumed that the impairment of allantoid vessels reduced in the intensity of oxidative processes in embryonic tissues. The decrease of blood pH, resulting from the carbon dioxide accumulation, set the sex differentiation in flavour of males.

        Key words: ultrasound, embryo, sex