Background and aims: Promotion of workers’ health and safety is one of the main tasks of managers and planners. One of the important sciences that can assist managers to achieve this gool is ergonomics. This article presents results of workload and job satisfaction survey in a heavy metal components manufacturing company in Tehran, in 2010. Methods: This cross sectional study conducted by survey of all operational workers. Workload is survived by NASA-TLX questionnaire that contained six dimensions and job satisfaction evaluated by short version of Minnesota questionnaire . Results: Job satisfaction questionnaire ’s reliability which assessed by Cronbach’s Alpha was 0.91. In addition, data analysis results declare that the average job satisfaction scale was 65 and at medium level and workload with 85.11 as average scale was at the high level. Effort and physical loads were two dimensions which have high amount in the workload In addition, no statistical significant relation was observed between the total job satisfaction score and workload score. (p<0.05). While the performance dimension showed a positive relationshipwith job satisfaction, frustration demonstrated a negative relationship with job satisfaction. Conclusion: In order to improve the work conditions the administrative and technological controls should be implemented and actions need to be taken to modify workload dimensions specially, two dimensions with the high amount and dimensions that have relationship with job satisfaction