U.S. Department of Health and Human Services and its agencies:

Agency for Health Care Research and Quality

Centers for Disease Control

• Diseases & Conditions
  
• Emergency Preparedness & Response
  
• Environmental Health
  
• Healthy Living
  
• Injury, Violence & Safety
  
• Life Stages & Populations
  
• Travelers' Health
  
• Workplace Safety & Health
  

Centers for Medicare and Medicaid Services

Food and Drug Administration

• Human Drugs
  
• Food Safety
  

National Institutes of Health

• National Center for Complementary and Alternative Medicine
  
• NIH Health Information Index
  
• National Library of Medicine(includes Medline)
  

National Center for Health Statistics

• Published Reports
  
• Life Tables
  

Office of Public Health & Science

Pandemic and Avian Flu

Health Information - Other Government Agencies

Environmental Protection Agency

• Office of Ground Water and Drinking Water
• AIRNow (EPA and other government agencies)

Federal Trade Commission--Diet, Health and Fitness

Occupational Safety and Health Administration

Recalls.gov
Alerts from six federal agencies concerning unsafe, hazardous, or defective consumer products, motor vehicles, boats, food, medicine, cosmetics, and environmental products.

U.S. Consumer Gateway--Health

U.S. Department of Agriculture Food Safety and Inspection Service

State and International Health Organizations

Texas Department of State Health Services (DSHS)

World Health Organization