The Lothians and Border Horse was a Yeomanry regiment, part of the British Territorial Army. It was ranked 36th in the Yeomanry order of precedence and was based in the Scottish Lowland area, recruiting in the Lothians – East Lothian (Haddingtonshire), Midlothian (Edinburghshire), and West Lothian (Linlithgowshire) – and along the border with England, particularly Berwickshire. It amalgamated with the Lanarkshire Yeomanry and the Queen's Own Royal Glasgow Yeomanry to form the Queen's Own Lowland Yeomanry in 1956.

Yeomanry is a designation used by a number of units and sub-units in the British Army Reserve which are descended from volunteer cavalry regiments that now serve in a variety of different roles.