Barnsley have announced that Dennis Souza, Marciano van Homoet, Diego Leon and Kyle Letheren will all exit the club this summer.
Souza has made 87 appearances for the Tykes since moving to Oakwell in 2007, while Van Homoet has played 42 times after joining at the same time.
Leon has also been a regular in his year-and-a-half with the club, while Letheren has made just one appearance.
The contracts of all four players expire at the end of June and they will be allowed to leave and look for new challenges.
Meanwhile, discussions are ongoing with Rob Kozluk, Jon Macken, Luke Steele, Luke Potter and Michael Coulsen.
Barnsley are speaking with the five players about extending their current deals beyond the summer.