Our current understanding on the pathogenesis of abdominal aortic and intracranial aneurysms is limited, but genetic and environmental factors as well as their interactions are likely to play important roles in the development and rupture of aneurysms. To identify genetic factors contributing to these diseases, we are carrying out genome-wide screening studies, which require a large number of patients and family members. Current methods of finding patients who qualify for genetic studies are, however, often costly and ineffective. To improve patient recruitment, a Web site was developed (cmmg.biosci.wayne.edu/ags). The site gives general information about our study, solicits participation into the study, and provides links to relevant medical and educational sites. During the time period of July, 1999, to December, 2000, the site received 5, 108 visits (13 visits/day). Approximately 20 research study applications are received each month. A total of 49% (57/117) of the individuals responding to the aortic aneurysm and 63% (84/134) responding to the intracranial aneurysm study report at least two affected blood relatives in the family and, therefore, qualify for our genetic studies. In conclusion, Web-based patient recruitment is successful and provides an improved success rate due to the fact that the responders are more motivated to participate in research studies.