Growth of the World Wide Web is beginning to create new opportunities for direct patient access to health care resources. At the same time, advances in medical care have produced demographic shifts in which an increasing number of patients have sensory and physical disabilities that may limit their ability to access these new information tools. This study uses automated and manual methods to measure the compliance of 30 popular consumer health websites with the World Wide Web Consortium (W3C) content accessibility guidelines. Among these 30 sites, 22 failed to satisfy at least one W3C Priority-1 accessibility checkpoint, making it impossible for some groups of disabled users to access information from them. All websites failed to satisfy at least one Priority-2 checkpoint, making it difficult for some groups to access information from the sites. These results suggest that accessibility of many consumer health websites to disabled users is very limited. The health informatics community must become more aware of this problem, particularly because many critical accessibility problems may be easily addressed if they are recognized.