Llansantffraid-ym-Mechain is a large village (in the community of Llansantffraid) in Powys, Mid Wales, close to the border with Shropshire in England, about 7 miles (11 km) south-west of Oswestry and 8 miles (13 km) north of Welshpool. It is on the A495 road and is at the confluence of the River Vyrnwy and the River Cain. The population as of the 2011 UK census was 1,415. The community includes the village of Deuddwr and several hamlets.
Llansanffraid means "Church of Saint Bride" in the Welsh language, and ym Mechain refers to its location in the medieval cantref of Mechain and distinguishes it from other places with the same or similar names.
The name is based on the story of St Bhrid, who is said to have floated across the Irish Sea on a sod of turf, or to have been carried to Scotland by two oystercatchers. The followers of St Bhrid possibly set up new settlements known by the Welsh as Llan Santes Ffraid, Church of (Lady) Saint Bhrid.
In recent years the spelling of the village name, with or without a "t", has been a contentious issue (as it has been at Llansantffraid Glyn Ceiriog).