Background and Objective: Working in sitting posture, specially using a poorly designed chair is one of the critical risk factors in developing low back pain. Low back pain is one of the most common musculoskeletal disorders (MSDs) and has been reported to occur in 50-90% of all adults with recurrent rate of up to 90%. The objective of this study was to design and develop ergonomic chair for Iranian office workers. Materials and Methods: In this study, chair-related anthropometric dimensions of 303 Iranian office workers were measured in both genders. ANSI-HFES 100/1988 standard protocol was used for chair design. Finally, using a usability test, the designed ergonomic chair was assessed by 60 men and women office workers. Results: Using anthropometrics measurements and ergonomic criteria for chair design and also considering technical limitations, an ergonomic chair was made. Then this ergonomic chair was compared with old made chair designs. Office workers' assessments between old chair design and new one showed a significant difference. Conclusion: In this study, design and development of construction of an ergonomic chair was successfully made which could be applicable to Iranian office workers in order to provide their comfort and well being.