It is commonly accepted that public engagement with eHealth is beneficial. However, engagement is also variable. This article presents the findings of a review of published evaluation studies around eHealth services. A targeted search of MEDLINE, CINAHL and EMBASE returned 2622 unique abstracts. 50 articles met the inclusion criteria and were subjected to further analysis. 6 review articles were used for post hoc validation. Four main types of eHealth service or resource were identified: health information on the Internet; custom-built online health information; online support; and telehealth. 5 key themes emerged in terms of facilitators or barriers to engagement: characteristics of users; technological issues; characteristics of eHealth services; content issues; social aspects of use; and eHealth services in use. Recommendations arising from the review include: targeting efforts to engage those underserved by eHealth; maximizing exposure to eHealth across all sections of society; improving access to computers and the internet; appropriate design and delivery; ensuring content is relevant to different audiences; capitalizing on the interest in social computing; and clarifying the role of health workers in the delivery of eHealth.