EP3 is the short for the 3rd episode of a certain series. It can also refer to:
- Prostaglandin receptor EP3
- EP3 (Kleptones ep)
- EP03 - a Swedish electric locomotive used by the Polish railway operator PKP
- Half-Life 2: Episode 3 - an episodic video game sequel under development
- Lockheed EP-3 - an electronic surveillance turboprop aircraft, operated by the United States Navy
- Milwaukee Road class EP-3 - a U.S. electric locomotive used by the railway operator Milwaukee Road 1919-1957
- EP3 Honda Civic - the chassis code for the 2001-2005 Civic Si and Type R