Introduction. Despite the unique measures being taken at the Astrakhan Gas Processing Plant for personnel protection, the harmful exposure to the staff is not eliminated completely yet. Examination of the immune system is one of the methods of laboratory control over the gas-processing workers’ health and the system of measures for hygienic normalization of the working conditions. Materials and methods. The present study describes the working environment and evaluates the state of the immune system in workers with the use of the standard unified methods and approaches. A Brüel & Kjear 1302 multi gas monitor and a Tsvet-550 gas chromatograph were used to indicate pollutants. Examination involved one hundred sixty workers and 81 person from the control group (donors of Astrakhan Regional Blood Transfusion Center). The immune system was evaluated using the System 9000 Plus hematological analyser, Cyto FLEX LX flow cytometer, UNICO 2100UV specrophotometer, and KFK-3-03-ZOMZ photometer Results. The established set of the main unfavourable production factors includes air pollution of the work area with sulphur dioxide, nitrogen oxides, carbon, hydrogen sulphide, saturated and unsaturated hydrocarbons, and unfavourable microclimatic conditions. Occupational hazards cause in employees changes in the immune status including leukocytosis, lymphocytosis, changes in the composition of the lymphocyte population and T lymphocyte subpopulation, a decrease in the immunoglobulin content, lysozyme activity and phagocytosis index. Limitations. The study took into account only the effect of occupational hazards on the deviation of the immune status of workers engaged in natural gas and condensate processing. Conclusion. The authors consider the recorded changes to be adaptive. It suggests the possibility of normalization of the workers’ immune system functions with adequate rehabilitation measures.