Can informatics improve health? This paper answers yes, exploring its components, benefits, and effect on a wide variety of health-related activities. We first examine how information technology enables health informatics, supporting information management and knowledge creation through its four cornerstones. Success factors in using informatics are covered next, including human factors, the role of trained health informaticians, and the importance of matching informatics initiatives with business goals and establishing and measuring value. We demonstrate the potential effect of the Internet on health services through such e-health applications as enterprisewide patient records, state-of-the-art call centers, and data repositories. For current evidence that informatics is already improving health, we turn to such topics as disease management, telehealth, patient safety, and decision support. As more organizations move informatics from theory into practice and realize its value, they will transform inefficient processes and improve care for all.