Wales hooker Ken Owens and full-back Liam Williams have signed deals to remain at Scarlets.
Owens, 27 and Williams, 23, have both played more than 240 times between them for the Llanelli-based region.
Scarlets head coach Wayne Pivac said securing captain Owens and Williams on new contracts was key.
"Retaining players of both Ken and Liam's experience and quality at the Scarlets is vitally important for the future of this region," Pivac said.
"Having experienced players, with great leadership qualities and genuine passion for our region, commit their futures to Parc y Scarlets, reinforces our intentions and ambitions to compete on the highest level and continue to strive to reach our potential."
Morriston product Williams, who has won 18 Wales caps, tweeted: "Pleased to announce I have signed for @scarlets_rugby for another two years!"