The article presents the results of blood testing of cats with obstructive bronchitis for specific immunoglobulin E in order to confirm the allergic etiology of the disease. The study involved 16 animals, of which an increased level of specific IgE was detected in 12 animals, 1 cat had uncertaine result, and only 3 animals showed a level within the physiological norm. Comparing the ob-tained results with the data of allergic skin intradermal testing, it can be seen that the largest number of registered allergic reac-tions is associated with a high level of spe-cific immunoglobulin E in the blood serum of animals, immunized by antigens, coming from the environment. That is, the antigens of house dust mites, especially mites of the genus Dermatophagoides farinae and Dermatophagoides Pteronyssinus. Thus, the proportion of animals that had an allergic reaction to these ticks was 56.3 %. We ob-served slightly lower allergenicity for ticks of the genus Tugorhadis putrescentiae (37.5 %), Acarus siro (37.5%). Less than 7 % of allergic reactions were observed to antigens of herbs, in particular, meadow thymothy (phelum pretense), white Marion (Chenopodium album L.) and plantain ma-jor (Plantago major). There was no immu-nological reaction to plant components: hazel (Corylus), common wormwood (Artemisia vulgaris). The results obtained using enzyme immunoassay (ELISA) were highly common with the results obtained during intra-dermal allergen testing. We can conclude that determining the level of IgE immunoglobulin in the blood of cats with signs of OB is an objective diagnostic criterion for confirming the allergic nature of obstructive bronchitis in cats.