Abstract. This work aimed to identify harmful factors in the production environment, identify risk factors, and assess their impact on the health of workers of the Ferghana Oil Refinery Plant. The research was conducted in 2010-2014 at the Fergana Oil Refinery. Sanitary and hygienic, labouratory, calculation and statistical methods of research were used to achieve the goal. The research results showed that the activity of professional groups of the main production shops of the refinery is accompanied by an unfavourable impact of a complex of factors of the production environment and labour process. The workplaces of these categories of specialists correspond to the general class of working conditions according to the hygienic classification - 3 class 1, 2, 3 and 4 degrees (3.1, 3.2, 3.3, and 3.4), where the high level of gas pollution, industrial noise and vibration, the severity of the labour process is observed. The technological cycle of production, consisting of sequential production operations, based on a multistage chain of chemical reactions, allowed identifying one of the leading harmful production factors - chemical. The composition of chemical pollutants of the working zone included a wide range of gases and chemical substances: carbon monoxide, sulphur dioxide, hydrogen sulfide, chlorine, toluene, benzene, acetone, hydrocarbons, kerosene, mineral oils, phenol, sulphur oil, gasoline, methylethyl ketone, diesel fuel. Thus, based on the obtained research results, the nature and intensity of unfavorable production factors have been revealed, the level of professional risk for the employees' health has been assessed, the risk factors determining the employees' professional health have been identified, the priorities in implementation of preventive measures at the enterprise have been determined.