The effect of nitric oxide (NO) supplied to the sweep gas of the oxygenator on the formation of gaseous microemboli during cardiopulmonary bypass has been studied in animal experiments (female pigs). It was shown that NO added to the sweep gas of the oxygenator during cardiopulmonary bypass significantly decreased the number and volume of microemboli (the number of microemboli over 1 h of cardiopulmonary bypass was 1197 (568; 2436) vs 55,478 (15,217; 331,480) in the control; p=0.016). The decrease in the number and volume of all bubbles was accompanied by a significant decrease in the concentration of neuron-specific enolase, a marker of brain injury, 6 h after the end of cardiopulmonary bypass to 7.7 (7.5; 8.7) ng/ml vs 11.2 (9.2; 18.3) ng/ml in the group without NO (p=0.047).