Failure Modes and Effect Analysis (FMEA) is a systematic method for identifying the factors that a product or process encounter with them, and identifying their results and effects. The aim of this study is to evaluate the potential occupational risks in different parts of the one of oil refinery in central Iran by using risk assessment techniques. This cross- sectional study was conducted in Shiraz Refinery and relationship RPN(Risk Priority Number) with tasks e.g. milling, welding, transportation handling and etc. were studied in this company. The findings showed that transportation and handling and then external surface scraping achieved the highest of RPN before and after corrective measures (200,210) and (72, 84) respectively. While RPN for welding and drilling (punching the external surfaces) before and after corrective measures are (144,120) and (24, 36) respectively. But hazard severity curve show tasks with lower RPN in comparison with those have higher RPN are more important of injury severity. some of tasks e.g. handling, transportation and milling have high RPN and by using effective control measures can eliminate or control hazards. Then Failure Modes and Effect Analysis is a useful and efficient for hazard assessment.