The future of the U.S. health care system has been the subject of heated debates prior to almost every recent U.S. presidential election. The United States is the only industrialized country that does not provide nationwide health coverage to all its citizens. In addition, the U.S. health care system has to face other challenges. In a 1999 study, it was estimated that between 44,000 and 98,000 American die each year from medical error and inappropriate treatment. Adoption of Electronic Health Records (EHR) systems can extend the efficiencies and effectiveness of health care services in health professionals’ offices and improve the health care quality for patients. An important issue in using EHRs in different health care organizations is the exchange of information and data sharing among different EHR systems. The major problem facing the U.S. health care system is the integration of health information to construct a large-scale ‘network of networks’. Health care organizations throughout the nation have recognized the importance of a transition from the current highly fragmented and disconnected health care information system to a secure and reliable nationwide health care information network for sharing critical health information at the point the clinical decision has to be made. The main goal of Nationwide Healthcare Information Network (NHIN) is to develop a secure, reliable, and interoperable infrastructure that all patients, healthcare providers, and other health care related organizations -like health insurance companies, public health centers, and health care research institutes- will be able to create, update and access the health information they need, at the time, and in the form that is useful regardless of the origin of data.