Monmouth (Welsh: Mynwy) was a county constituency[n 1] of the House of Commons of the Parliament of the United Kingdom (at Westminster).

The last MP for Monmouth was the Conservative David T. C. Davies, elected in 2005 and a former member for the Senedd seat of the same name.

Merthyr Tydfil and Rhymney, however, straddles the boundary with the preserved county of Mid Glamorgan.

It covered most of the local authority of Monmouthshire, with the main towns being Chepstow, Monmouth and Abergavenny.

This general pattern was maintained until 1983, nine years after the administrative county they were based on had been abolished, but there were some boundary changes during the 1918 to 1983 period.

[4] The constituency was redefined again for the 1955 general election, taking account of new local government boundaries.