Middlesex is the name of several places:

• England:
  • Middlesex, a traditional county of England
    • Middlesex County Cricket Club
    • Middlesex University
• Canada:
  • Middlesex County, Ontario, Canada
• In the United States of America:
  • Middlesex County, Connecticut
  • Middlesex County, Massachusetts
  • Middlesex, New Jersey
  • Middlesex County, New Jersey
  • Middlesex, New York
  • Middlesex, North Carolina
  • Middlesex Township, Pennsylvania
  • Middlesex, Vermont
  • Middlesex County, Virginia

Middlesex is also the title of a novel by Jeffrey Eugenides.