Background: The integration of healthcare information systems is one of the most urgent priorities of healthcare organizations. Middleware has a major role in the integration of hospital information system (HIS). The purpose of this study is to determine the type of middleware used, their configuration and integration approaches in the hospitals of the research community.Methods: This study was descriptive in nature and was conducted in the form of a survey, with data being gathered via a self-structured questionnaire, in 2014. Seventeen hospitals affiliated to TUMS that have the HIS were recruited for this study. The questionnaire consisted of three parts. Simple statistical analysis was used to determine the integration status of HISs.Results: The most striking result to emerge from the data is that 64.7% of HISs had database-oriented middleware. Approximately half of surveyed HISs (41.2%) used synchronous mechanism and almost two-thirds of them (70.2%) used web service. Although, 17.2% of HISs use service-oriented integration approach, but the overall response to this question was poor.Conclusion: The result of the study indicates that the database-oriented middleware facilitate accessibility of the databases, on a variety of platforms. It might be related to the variety of company those developed the HISs. The result showed that the using web services could be helpful to application integration. The results of this investigation show that the HIS companies and healthcare facilities must be considered to the standards of interoperability for development and selection of the systems. Further research should be done to investigate the integration status of HISs in cross-national level and with other information systems in the field of healthcare.