The objective of the present experimental investigation was to study peculiarities of the toxic action of ammonia vapours on the respiratory organs. The experiments were carried out on 20 white rats. The animals were placed in a special chamber and exposed to ammonia vapours. The histological examination of different internal organs laid emphasis on the lungs and upper respiratory tract. Changes in blood pH values were measured. It is shown that the severity of inhalation intoxication with ammonia vapours depends on the development of asphyxia as a result of laryngeal oedema and spasm. Ammonia vapours penetrating into the bloodstream cause alkalinization of the blood. The results of the study open up prospects for the development of new approaches to the treatment and prevention of laryngeal oedema, modulation of pH values in the blood and mucous membrane of the respiratory organs.