Background and aims :Prevalence of musculoskeletal disorders (MSDs) is high among office workers. Long time seated posture, working with computer, repetitive movements and inappropriate environmental conditions may have causal effects in these disorders. High prevalence rate of MSDs makes ergonomics assessment and working conditions improvement necessary. Designing an assessment checklist and calculating ergonomics indices can be useful in this evaluation. This study was conducted with the objectives of determination of prevalence rate, ergonomics assessment of working conditions and determination of factors associated with MSDs among office workers.

 Methods:In this study 400 randomly selected office workers participated. Nordic musculoskeletal disorders questionnaire was applied to determine prevalence rate of MSDs. Working conditions were assessed by the designed ergonomics checklist and ergonomic risk factors were identified. Data were analyzed using statistical tests including t-test, Chi-square and test of proportion by SPSS software (Version 12.0).

 Results:The highest prevalence rates of MSDs were reported in lower back and neck regions (49% and 47%, respectively). Statistical analysis revealed that there were significant association between occurrence of MSDs and calculated ergonomics indices (P<0.05). The mean of ergonomics index among those suffered from MSDs were less than other healthy workers indicating inappropriate ergonomics conditions. Calculation of OR also revealed that ergonomics conditions was associated with MSDs occurrence among workers (P<0.05). Totally, 53.3% of the office workers studied had poor working conditions. Awkward working posture and inappropriate workstation design were recognized as the main risk factors in the office workplace.

 Conclusion:Most ergonomics problems were originated from bad postures and inappropriate design of workstation. Any interventional program for working conditions improvement should, therefore, be focused on these items. Inappropriate table height, improper position of monitor and other office equipment , lack of adjustability of seat and back rest of chair and deep seat were among factors to be considered for working condition improvement.