Middlesex is the name of several places:

• In England:
  • Middlesex, a traditional county of England, The original use of this place name.
    • Middlesex County Cricket Club
    • Middlesex University

• In Canada:
  • Middlesex County, Ontario, Canada

• In the United States of America:
  • Middlesex County, Connecticut
  • Middlesex County, Massachusetts
  • Middlesex, New Jersey, a borough.
  • Middlesex County, New Jersey
  • Middlesex, New York, a town.
  • Middlesex, North Carolina
  • Middlesex Township, Pennsylvania
  • Middlesex, Vermont, a town.
  • Middlesex County, Virginia

• In Jamaica
  • Middlesex is one of the three sub-divisions of the island

Middlesex is also the title of a novel by Jeffrey Eugenides that won the 2003 Pulitzer Prize for Fiction.