40th Regiment

• 40 (Ulster) Signal Regiment
• 40th (2nd Somersetshire) Regiment of Foot
• 40th (The King's) Royal Tank Regiment
• 40th Armor Regiment
• 40th Battalion (disambiguation)
• 40th Brigade (disambiguation)
• 40th Cavalry Regiment (United States)
• 40th Division (disambiguation)
• 40th Fighter Aviation Regiment
• 40th Illinois Volunteer Infantry Regiment
• 40th Infantry Regiment (United States)
• 40th Iowa Volunteer Infantry Regiment
• 40th New York Volunteer Infantry Regiment
• 40th Regiment Royal Artillery
• 40th Squadron (disambiguation)
• 40th Wisconsin Volunteer Infantry Regiment
• 40th/41st Royal Tank Regiment