ETR may refer to:

  • Etravirine (Intelence/TMC125), an antiretroviral drug used in HAART to supress HIV replication
  • East Turkestan Republic (disambiguation)
  • ElettroTreno, a series of Italian high-speed trains
  • Express Toll Route, in Canada
  • Eastern Test Range, a rocket testing area off of Cape Canaveral
  • Effective Tax Rate, a method of expressing the overall percentage of a company's revenue which is paid in taxes
  • Entergy Corporation, NYSE stock symbol
  • Essex Terminal Railway, a short line railroad in Canada
  • Elstree Airfield, the IATA airport code
  • Exponential trace function of linear algebra, usually written in lower case (etr)