The study describes the quality of working conditions of the Rolling Personnel (Machinist) at the national railway company of Congo and its impact on their performance and health. 50 employees compose the sample. The descriptive method, the direct observation, the interview and the job analysis form of Professor Kabambi Ntanda from the University of Kinshasa constitute the research tools. The results indicate that these personnel work in extremely bad working conditions and present dangers. As a result, the employer should intervene as soon as possible to save the physical and mental health of this Personnel.