18th Regiment

18th Regiment or 18th Infantry Regiment may refer to:


 * 18th Infantry Regiment (Imperial Japanese Army)
 * 18th Alpini Regiment, a unit of the Italian Army
 * 18 (UKSF) Signal Regiment, a unit of the British Army
 * 18th Royal Hussars, a unit of the British Army
 * 18th Infantry Regiment (United States), a unit of the United States Army
 * Royal Irish Regiment (1684–1922) was formerly the 18th Regiment of Foot


 * American Civil War regiments :


 * Confederate (Southern) Army regiments
 * 18th Regiment Alabama Infantry


 * Union (Northern) Army regiments
 * 18th Illinois Volunteer Infantry Regiment
 * 18th Iowa Volunteer Infantry Regiment
 * 18th Regiment Indiana Infantry
 * 18th Regiment Massachusetts Volunteer Infantry
 * 18th Michigan Volunteer Infantry Regiment
 * 18th Wisconsin Volunteer Infantry Regiment