A complex clinical-hygienic study in employees of a petrochemical complex for the production of synthetic resins was conducted. The main hazardous factor in the working environment under the study was a chemical production factor which was represented by 2–3 class hazards. In general, the working conditions were closely matched to class 3.3 according to the level of a chemical factor. The priority classes of chronic non-infectious diseases among petrochemical workers revealed statistical evidence for association of the disease with the work, characterizing the professional risk to the health of the workers.