The Lammermuir Hills or Lammermuirs, in southern Scotland, form a natural boundary between Lothian and the Scottish Borders. They span the unitary authorities of East Lothian and Scottish Borders. They offer a traditional site for sheep grazing.

The hills are nowhere especially high, but steep gradients, exposure to the elements and a lack of natural passes combine to form a formidable barrier to communications between Edinburgh and the Borders. The hills are crossed by only one major road (the A68), which crosses the shoulder of Soutra Hill between Lauder and Pathhead, and is frequently closed by snow in winter. The main road linking Edinburgh to England (the A1) avoids the hills by following a circuitous route around the coast.