Most jobs in the oil and petrochemical industries are characterized by exposure to industrial noise, air pollution of the working area with harmful chemicals, dynamic and static loads, forced working posture, and nervous and emotional overstrain. The complex, long-term impact of these factors on workers leads to the development of fatigue, disruption of the adaptive mechanisms of the body and the formation of pathology of the hearing organ. These changes are most pronounced at the initial stages of the formation of professional hearing loss. In order to study the role of immune mechanisms in the pathogenesis of occupational hearing loss, major groups of immunoglobulins (A, M, G, E) in blood serum were determined. The identification of mature T-cell populations was carried out by indirect immunofluorescence method with monoclonal antibodies of the ICO series (CD3+, CD4+, CD8+, CD16+, CD20+) in 120 workers. The state of the immune status of employees of the main professions can be characterized by the presence of a tendency to form a secondary immunodeficiency state, manifested by the suppression of both cellular and humoral links. Violations of individual parts of the immune system among employees of «noise» industries reflect the level of adaptive reactions of the body and correlate with changes in the auditory analyzer and can develop long before the clinical manifestations of the disease. Identification of subclinical changes in the indicators of the immune system of the body of employees will allow timely preventive and pathogenetically justified rehabilitation measures, prevent the progression of the process and its transformation into professional hearing loss and preserve their ability to work for a long period.