Work Related Musculoskeletal Disorders (WMSDs) can be a result of complex interactions between physical, psychosocial, biological, and individual characteristics. However, the evidence on specific associations is still inconclusive. A previous study conducted at a Sterile Processing Department (SPD) in a local hospital established an association between perceived job demands and adverse body postures. However, causal inferences were not possible to establish given the study design. Consequently, the objective of this study was to determine if perception of mental workload causes workers to use more risky body postures. Objective and subjective assessment tools (REBA and NASA-TLX scores) were used as indicators of body postures and mental workload. The findings indicated that there is a positive relationship between the perception of workload (NASA-TLX scores) and adverse body postures (REBA scores) suggesting that people tend to adopt more awkward postures when they feel they are in a rush condition or they have more things to do