Objective: To assess the online contents and interactivity provided by health support group (HSG) websites representing a range of chronic diseases. Design: Survey of 80 HSG websites. Method: A checklist of website content was developed rating the level of information and advice, interactivity and online support provided by each HSG website. Each website was examined page by page using the checklist. A comparison of website characteristics by HSG income was made. Results: Information and advice: 97.5 per cent provided medical information and most provided some form of advice, especially about treatment (88.1 per cent); 93.75 per cent provided non-medical information with news items (77.5 per cent) and an events diary (61.3 per cent). Interactivity: all but one website had some form of interactivity but more complex content functions were less frequently present (e.g. self- evaluation questionnaire, 18.8 per cent) and tended to be restricted to larger HSGs. Online support: 52.5 per cent of websites offered a discussion forum and 63.8 per cent a helpline. Few websites (36.3 per cent) provided the date of the last update and where displayed it tended to be out of date (4.1 months). Accessibility for users with disabilities was limited with just 16.3 per cent offering manual adjustment of the website display. Conclusion: While HSGs are providing useful information and support, most are not yet exploiting the full potential of a website, with the interactive elements on these sites still in their infancy and not being regularly up-dated. (Contains 1 table.)