Aim. To study the processes of free-radical oxidation, antioxidant defense, energy metabolism, electrolyte metabolism, and cytokine system reflecting the state of the non-specific defense of the body in workers exposed to complex of toxic substances under the conditions of manufacturing, substantiating the importance of indicators of preclinical diagnosis of disease development risk.Methods. The study included 90 workers of JSC «Experimental Plant Neftekhim», 95 workers of JSC «Kaustic» and 101 workers of JSC «Ufa plant of elastomeric materials, products and structures». Materials for the study were blood, mixed saliva, gingival fluid and urine. The laboratory studies were performed to evaluate the free radical oxidation processes, antioxidant defense, energy metabolism, electrolyte metabolism, and cytokine system. Taking into account the features of industrial factors, particularly their effects on the workers bodies, routes of toxic compounds entry by inhalation, oral cavity and skin of the hands, three professional groups were formed (A, B, C). Group A included employees having constant contact with chlororganic compounds. The group B included persons who have constant contact with the higher and lower aromatic hydrocarbons. A group C consisted of employees who have constant contact with a mixture of chemicals: rubber compound containing carcinogens - benzo(a)pyrene, NDMA, nitrosodiethylamine; white carbon black, rubber dust, talc, amine compounds, sulfur dioxide, carbon monoxide. The control group consisted of employees of administrative and managerial staff.Results. The study revealed that one of the major pathogenetic mechanisms of action of chemical and petrochemical industry hazards is activation of free radical oxidation.Conclusion. Among the mechanisms of the influence of chemical contaminants of working environment a leading role play intensification of free radical oxidation processes, failure and/or inhibition of the antioxidant defense components.