Background and Objective: Considering the importance and high prevalence of musculoskeletal disorders, this study aimed to investigate the role of mental workload, fatigue, and sleep quality in the development of musculoskeletal disorders. Materials and Methods: This study included 243 employees working at Borujerd health center. The participants were selected based on simple random sampling. The data were collected using the Cornell Musculoskeletal Disorders Questionnaire, Sophie Fatigue Questionnaire, and Pittsburgh Sleep Quality Questionnaire. Moreover, the Subjective Workload Assessment Technique was utilized to evaluate the mental workload. The data were analyzed using SPSS software (Version 18) through the Pearson correlation coefficient, the Chi-square test, and regression analysis. Results: According to the results of this study, back pain was ranked as the most prevalent disorder. The results of the correlation analysis showed a significant association between mental workload and fatigue with musculoskeletal disorders (P≤0.02). Moreover, a significant relationship was observed between sleep quality and musculoskeletal disorders (P≤0.02). Conclusion: It can be concluded that reduced workload and fatigue, as well as improved sleep quality, can decrease the risk of musculoskeletal disorders among the staff.