Electronic health information exchange allows physicians and hospitals to access and share clinical data for individual patients with other health care personnel when and where these data are needed and across organizational and geographic boundaries. The timely exchange of electronic information, such as clinical summaries, laboratory results, radiology reports, and medication lists, may improve patient safety and outcomes, increase the efficiency of care, and prevent the unnecessary duplication of tests. The delivery and payment reform engendered in Medicare and Medicaid by the Affordable Care Act are incentives for the coordination of care across diverse locations, which also benefits from the efficient exchange of health information.