91st Division
In military terms, 91st Division or 91st Infantry Division may refer to:
Infantry divisions:
- 91st Infantry Division (German Empire)
 - 91st Infantry Division (Wehrmacht)
 - 91st Division (Israel)
 - 91st Division (Imperial Japanese Army)
 - 91st Division (Philippines)
 - 91st Division (United States)
 - 91st Rifle Division, Soviet Union
 - 91st Motor Rifle Division, Soviet Union
 
Aviation divisions:
- 91st Air Division, United States