Ulster have confirmed that Robert Baloucoune, Luke Marshall, Alan O'Connor and Aaron Sexton have all committed to the province until the summer of 2023.
Luke Marshall has been capped 11 times for Ireland, although his last came in a June 2017 victory over Japan in Tokyo.
He's played 144 times for the northern province having joined the Ulster academy in 2009 and come through the ranks.
"Luke is one of our longest-serving players and brings an excellent ability to read the game and organise defences," Head Coach Dan McFarland said of the 29-year-old.
"I'm delighted that he’s committed to Ulster for a further two seasons, and we look forward to also seeing him back from injury soon."
Enniskillen-born Baloucoune was named in Andy Farrell's Ireland development squad for last year's Six Nations, but he suffered an unfortunate injury at the end of last summer which saw him tear his hamstring off the bone in training.
McFarland added: "He's been unlucky with injury this season, but he is not far off making his return which we’re all looking forward to."
Dubliner O'Connor has been with Ulster since 2012 while Sexton will be involved with the province's development programme for another season after making his senior debut against Edinburgh in the Guinness Pro14 in November.