Introduction: I ssues related to organizations and users are among factors influencing successful implementation of information systems. These factors should be taken into account by managers. The purpose of this study was to examine the influence of supervisors and workgroup on Hospital Information System (HIS) acceptance by

  users in medical hospitals of Tehran (former Iran) University of Medical Sciences.

  Methods: After the literature review, a primary model including seven variables influencing HIS acceptance was proposed. A questionnaire including 121 questions based on the variables was developed, the validity and reliability of which were tested and confirmed by an expert panel and through Chronbach Alpha. The population of the study were 400 HIS users in hospitals selected by stratified random sampling method. To confirm the model and determine the relationship between variables, Structural Equation Modeling (SEM) method was used by applying LISREL Software.

  Results: The result of Normed Chi Square Index ( χ ² /df= 2.49) showed that the model had fitness with the collected data. According to the model, supervisers and workgroup influenced Perceived Ease of Use, Perceived Usefulness, and Satisfaction which affected users Behavioral Intention to use Hospital Information System in these hospitals (P-value= 0.0054).

  Conclusion : Considering the goodnesss of fit indices, it is concluded that supervisors and workgroup factors have the potential to influence HIS acceptance. The application of the suggested model could increase the possibility of HIS acceptance in hospitals under the study.