The Scarlets ran in six tries to put their old rivals to the sword in front of 6,471 fans in the Welsh Premiership at Stradey Park. Having beaten Swansea 62-6 at the same venue in the Celtic League in October, this was another convincing display by the home side.
Llanelli got off to a flying start with a try from Irish international Simon Easterby and full back Barry Davies quickly followed suit. Stephen Jones, who ended the night with 13 points converted both and the Scarlets were on their way.
To their credit, the Swansea defence never shirked their duties. If they had the home side would have scored 10 or more tries.
By the interval Llanelli had grabbed a third try through Matthew Watkins, who rounded off a thrilling break by co-centre Leigh Davies, and Jones's boot helped his side up to 24 points at the half-way mark.
For their part, Swansea kept in touch with two Gavin Henson penalties and then a try by former Wales wing Matthew Robinson which Henson converted. That meant they trailed by only 11 points at the break.
But the second half saw Llanelli run in a further three tries as they built towards their crucial Heineken Cup clash with Pool 3 leaders Bourgoin at Stradey Park on Friday night. Scott Quinnell played through the whole of the second half as he got himself ready for the big Euro challenge and Guy Easterby, Dafydd Jones and Garan Evans grabbed the extra tries.
Henson added a third penalty for Swansea and then converted an injury time try by Wales centre Mark Taylor.
Scorers: Llanelli: Tries: S Easterby, B Davies, M Watkins, G Easterby, D Jones, G Evans; Cons: S Jones 5, G Bowen; Pen: S Jones. Swansea: Tries: M Robinson, M Taylor; Cons: G Henson 2; Pens: G Henson 3.