31st Brigade
31st Brigade or 31st Infantry Brigade may refer to:
- 31st Brigade (Australia)
- 31st Brigade (France)
- 31st Mechanized Infantry Brigade (Greece)
- 31st Indian Brigade of the British Indian Army in the First World War
- 31st Indian Infantry Brigade of the British Indian Army in the Second World War
- 31st Mechanized Brigade (Soviet Union)
- 31st Mechanized Brigade (Ukraine)
- 31st Air Defense Artillery Brigade (United States)
- 31st (North Midland) Anti-Aircraft Brigade (United Kingdom)
- 31st Brigade (United Kingdom)