Created in 1995, the seat is held at Westminster for Labour by Nick Ainger, who had a majority of 22.6% over the Conservatives.
The previous Pembroke seat, which forms a large part of the constituency, was in long-term Conservative control until 1992.
Both the former Carmarthen and Pembroke seats have been represented by prominent political figures.
Former Welsh secretary Nicholas Edwards, now Lord Crickhowell, was the MP for Pembroke for 22 years.
Carmarthen was also the scene of Plaid Cymru's electoral breakthrough when Gwynfor Evans won the 1966 by-election.
The area contains widespread farming areas as well as districts on the south Pembrokeshire coast such as Tenby and Saundersfoot, which are heavily dependent on tourism.
Pembroke Dock provides a sea ferry link with Ireland. Pembroke town has suffered due to the decline in the oil refining industry, although the announcement of a major new investment in the town's refinery in July 2000 provided a fillip to the area.
South Pembrokeshire is sometimes referred to as “Little England beyond Wales” due to the high level of inward migration and the limited number of Welsh speakers which contrasts with the relative prevalence of Welsh speakers in Carmarthenshire.