Clinical experience suggests that the Internet is increasingly becoming a resource for patients seen in medical genetics. A prospective analysis was performed exploring patient use of the Internet prior to attending a medical genetics appointment. We administered 200 questionnaires assessing: 1) the frequency of patient use of the Internet for genetic information, 2) factors associated with Internet use, 3) patient assessment of the value of the information, and 4) patient views of the responsibility of medical genetics professionals to be familiar with Internet information. Results show that 77% (153/200) of patients have access to the Internet of which 29% (44/153) report searching the Internet for genetic information. A correlation was found between patient use of the Internet and reason for referral (p<0.001), presence of a specific diagnosis (p<0.001), and frequency of Internet use (p<0.05). Overall, 80% (33/41) of patients found Internet information useful. Seventy-four percent (115/155) believed that medical genetics professionals have a responsibility to review relevant Internet sites for accuracy and 80% (123/153) felt that professionals should provide their patients with appropriate and useful Internet sites. These results suggest that the role of medical genetics professionals is changing as a result of the development of the Internet.