Abstract Improvement of chymosin (rennin) production is limited by a prolonged extraction process. An ultrasonic method of chymosin extraction was developed to increase efficiency. The application of ultrasonic energy significantly reduced time required for the extraction process as a result of abomasum tissue dispersing, destruction of the cells, intensive blending, separation of particles, and increase of the interphase abomasum-extraction medium. The ultrasonic extraction process significantly increased yield of chymosin. Optimal technological parameters for extraction and properties of extraction medium were established: time of ultrasonic treatment (45min), intensity of ultrasound (3.34 W/cm2), temperature of extraction medium (15°C), NaCl concentration in solution (5%), ratio of abomasum to extracting solution (1:18), NaCl concentration in solution (5%), ratio of abomasum to extracting solution (1:18), pH of solution (4.2 to 4.3), time of chymosin extract activation (7h), degree of abomasum shredding (strips 5 to 8mm wide), and time of abomasum swelling (20min).