Internet use for health information by both practitioners and consumers continues to expand geometrically. The impact of Internet on practice, access and health decisions is considerable and will probably grow to the predominant mode of health information delivery in the coming years. As the growth of this unregulated global bulletin board continues, how do we assure the quality of the information retrieved by professionals and patients? What are the indicators of quality? How should we measure impact? How do authoritative sources get the attention and who should decide? What should practitioners recommend? What should medical teachers advise trainees? This review of Internet content, access and application considers the history, patterns of use, evaluation studies and specialty examples. A few authoritative sources are recommended and that recommendation is justified. Changes in health care delivery must take best advantage of the Internet with least disruption to the important principles of practice and patient relationships. The health community needs effective interaction with medicine's inevitable partner, the Internet.