Crude oils are complex mixtures containing many different hydrocarbon compounds that vary in appearance and composition from one oil field to another.During refinery process, many emissions like volatile organic compounds, particulates, and some serious gases e.g. ( hydrogen sulfide, sulfer dioxide, carbon monoxide, carbon dioxide, nitrogen dioxide, and ammonia) are produced with wide range of toxicities.Egypt has eight refineries (El Mex, Amerya, El Suez, El Nasr, Mostorod, Tanta, Asyut and Wadi Feiran) with a combined crude oil capacity in excess of 578,000 bbl/d.So this comparative cross sectional study was carried out to determine the adverse respiratory health effects among oil refinery workers of Cairo Oil Refinery Company (CORC) at Mostorod that exposed to the emitted pollutants by the refinery including many gases e.g. (SO2, H2S, NO2, NH3, CO and CO2), volatile organic hydrocarbons and particulates. Also it aimed to identify some occupational , environmental and personal risk factors associated with adverse respiratory health effects and to recommend some important preventive and safety measures that can be of great help for such workers.The present study included the morning work shift workers of Cairo Oil Refinery Company at Mostorod. the total number of workers were 187, 113 workers were exposed to different emissions (gases, hydrocarbons, and particulates) present in the work environment of the company and 74 workers were non-exposed as they were administrative staff.All workers were subjected to full medical history, occupational history, physical examination, pulmonary fuction using vitalograph, 18 workers of maintenance section were subjected to plain chest X-ray P.A view.