By mehanographic method, contraktile responses of the airways smooth muscles in experimental bronchial asthma in porpoises intact and incubated with interleykin-5, were studied. Sensitization of ovalbumin animals results in development of hypersensitivity to inhalation of the fiber with external attributes of infringement of bronchial passableness such as cough and a shortness of breath. Morphologically the process is accompanied by destruction of epithelium of the bronchial tubes, development of an immune inflammation in a bronchial wall, and a hypertrophy of the muscular layer. In the sensitized animals, development of hyper-responsiveness of the airways smooth muscles to histamine was obvious as shown in a significant decrease of the threshold concentration and an increase in the maximal amplitude of reduction. Interleukin-5 was shown to strengthen this process. Responses to holinergic and R2-adrenerdic influences practically did not change. The data obtained corroborate the hypothesis of development of the interleukin-5-depending bronchial hyper-responsiveness in absence of eosinophile damage in the mucous membrane of the bronchial tubes.