45th Regiment

• 45th (Leeds Rifles) Royal Tank Regiment
• 45th (Nottinghamshire) (Sherwood Foresters) Regiment of Foot
• 45th Arkansas Infantry (Mounted)
• 45th Brigade (disambiguation)
• 45th Cavalry (India)
• 45th Detached Reconnaissance Regiment
• 45th Division (disambiguation)
• 45th Garrison Regiment, Royal Artillery
• 45th Illinois Volunteer Infantry Regiment
• 45th Infantry Regiment (Imperial Japanese Army)
• 45th Infantry Regiment (United States)
• 45th Iowa Volunteer Infantry Regiment
• 45th Light Anti-Aircraft Regiment, Royal Artillery
• 45th New York Volunteer Infantry Regiment
• 45th North Carolina Infantry
• 45th Ohio Infantry
• 45th Rattray's Sikhs
• 45th Regiment Kentucky Volunteer Mounted Infantry
• 45th Regiment Massachusetts Volunteer Infantry
• 45th Squadron (disambiguation)
• 45th Tennessee Infantry Regiment
• 45th United States Colored Infantry Regiment
• 45th Virginia Infantry
• 45th Wisconsin Volunteer Infantry Regiment