Centers for Disease Control:
The U.S. government publications covering infectious disease, chronic diseases, environmental hazards and injuries. Some information available in Spanish. Includes sections on health hoaxes and rumors and travelers' health issues. Centers for Disease Control and Prevention.

Health A to Z: HealthAtoZ is a comprehensive, well-integrated health and medical resource developed by healthcare professionals. HealthAtoZ's aim is to partner with consumers so that every individual and family can better manage their health.

InteliHealth: Aetna InteliHealth has become one of the leading online health information companies in the world. This consumer-friendly health information is reviewed and approved by leading medical and dental experts.

Medical Matrix: Medical Matrix is a free directory of selected medical sites on the Internet. Each site listing has been carefully evaluated by reviewers from a panel of physicians and medical librarians. Free registration.

PDRhealth: Searchable information and news on common health conditions. Free registration. Medical Economics.

National Institutes of Health: The world's largest medical library. A-Z index of NIH health resources, clinical trials, MedlinePlus, health hotlines.