Joshua E Richardson, Erika L Abramson, Rainu KaushalCenter for Healthcare Informatics and Policy, Weill Cornell Medical College, New York, NY, USAAbstract: Health information exchange (HIE) is a key component of health care reform that enables clinical data sharing between providers, patients, and health care organizations. The value of HIE rests in the promise that more efficient and effective access to clinical data will improve patients’ condition-specific outcomes relative to the costs. For example, improvements in outcomes may result from fewer medical errors and improved adherence to evidence-based recommendations, whereas reductions in costs may result from fewer duplicate tests and improved care coordination. However, even though health care reform efforts promote HIE as a way to improve care and curb costs, few studies demonstrate these results. We have organized the available evidence at national and regional levels to report on costs and benefits associated with HIE, and identify potential areas of future research.Keywords: health information exchange, interoperable systems, health information technology, economic assessment, evaluation