The authors have set the goal to experimentally study the effect of the Triazavirin antiviral drug on pigs, as well as the histological structure, the state, and abnormalities in several organs and tissues after the administration of the Triazavirin antiviral drug. For the experiment, an experimental group of 25 piglets has been formed. The animals have been kept in the same zoohygienic conditions, have had the same diet according to the age and the feeding technology. The piglets in the experimental group with symptoms of respiratory system impairment have received the Triazavirin antiviral drug as experimental etiological therapy. The drug has been given to the experimental animals with drinking in the form of an aqueous solution. After the slaughtering of the experimental animals at a meat processing factory, pieces of organs have been collected for histological examination — the trachea, the bronchi of the lungs and adjacent lymph nodes, the liver, the kidneys, the spleen, the heart, and the ovaries. During the experiment and administration of the Triazavirin antiviral drug in the indicated doses, no lethality has been observed in the experimental piglets. In the experimental group, the piglets' state has improved, the temperature has returned to normal, the appetite has improved, and there have been no clinical signs of respiratory impairment. As a result of the experiment with the piglets during the histological studies of several organs, no significant deviations from the norm have been revealed in their structure. The organs of the respiratory system have stabilized and have had a morpho-histological structure close to normal, which is a positive result of the experiment. Analyzing the data of the histological studies, it may be concluded that the Triazavirin antiviral drug does not cause changes in the morphology of the tissues of the studied internal organs. Based on the above, the authors recommend using the Triazavirin antiviral drug as part of comprehensive etiological therapy for the treatment of the respiratory system in pigs, including the treatment of viral diseases.