The Internet provides patients, families, and health providers with unparalleled opportunities to learn, inform, and communicate with one another. This paper is a review of studies that have evaluated the impact of professionally facilitated Internet-based programs for diverse clinical populations on health outcomes, utilization, and user satisfaction. The findings suggest that some outcomes in certain groups can be moderately improved and that user satisfaction has been generally positive. Given the increasing need to provide timely and effective patient-centered care, a stronger evidence base for eHealth applications must be established before broader deployment of such programs will take place.