The Middlesex Regiment (Duke of Cambridge's Own) was a line infantry regiment of the British Army in existence from 1881 until 1966. The regiment was formed, as the Duke of Cambridge's Own (Middlesex Regiment), in 1881 as part of the Childers Reforms when the 57th (West Middlesex) and 77th (East Middlesex) Regiments of Foot were amalgamated with the county's militia and rifle volunteer units.
On 31 December 1966 the Middlesex Regiment (Duke of Cambridge's Own) was amalgamated with the other regiments of the Home Counties Brigade, the Queen's Royal Surrey Regiment, the Queen's Own Buffs, The Royal Kent Regiment and the Royal Sussex Regiment to form the Queen's Regiment.