title: 731 (disambiguation)
text: # 731 (disambiguation)
  
  731 was a common year starting on Monday (link will display the full calendar) of the Julian calendar. It may also refer to:
  
  * 731 (number)
  * 731 (The X-Files), the tenth episode of the third season of the American science fiction television series The X-Files
  * 731 BC, the ninth year of the 730s BC decade
  * 731 series, an AC electric multiple unit train type operated by Hokkaido Railway Company
  * Area code 731, an area code in the U.S. state of Tennessee
  * Battle of Hill 731, a fierce battle fought during World War II in southern Albania
  * Unit 731, a covert biological and chemical warfare research and development unit of the Imperial Japanese Army
  