Introduction: A hospital information system (HIS) is a comprehensive, integrated information system designed to manage the administrative, financial and clinical aspects of a hospital. As an area of medical informatics, the introduction of a HIS into a hospital was purported to reduce the time spent on administrative and clinical activities by electronic data processing. However, adoption has been slow, and a key concern has been that staffs will require more time to complete their work using HIS. And also Most of available HIS have lots of deficiencies in data gathering, so hospital managers decided to keep their paper records and same time use HIS. Most previous studies addressing this issue have been done with concentration on clinical staff activities. Methods: Comparative observational of the impact of a HIS on Medical Records Department time in four units: Admission Discharge and Transfer/ADT, Medical Filing and Retrieval, Medical coding/billing, and Medical Statistics. Measurements: We used a time-motion method to measure staff time spent in predefined activities. Medical Records staff monitored while using HIS and paper based system. 15 clerical medical records staff were observed treating 300 documents while still using paper-based records, and same persons were observed treating 400 patients' records with HIS. Results: Following HIS implementation, the use of the computerized system decreased the average total workload by 61.35% (from 66.41 to 23.93 m). Conclusion: Hospital Information System (HIS) reduces three nonclinical activities time noticeably which is vital to decision making and plays a crucial role in the success of the organization. [ABSTRACT FROM AUTHOR]