Fast bowler Tim Groenewald will leave Derbyshire at the end of the season.
Groenewald told the Division Two club that he wanted the leave, and Derbyshire have allowed him to begin talks with other counties.
Groenewald, 30, has been the lynchpin of Derbyshire’s bowling attack since joining the county from Warwickshire in 2008.
He took 42 wickets in 2012 to help them achieve promotion to Division One, and 45 last summer.
The 30-year-old has played 72 first-class matches for Derbyshire and taken 229 wickets, at an average of 29.
He has also taken 103 wickets in limited-overs formats and was capped by the club in 2011.
Elite Performance Director Graeme Welch told the club’s website: "Tim has been a terrific player for Derbyshire and we respect his decision to move on.
"We are absolutely committed to our long-term vision for success and we have an exciting crop of young seam bowling talent coming through with the likes of Ben Cotton, Tom Taylor, Matt Higginbottom and Greg Cork.
"Tim's decision creates a terrific opportunity for these lads and we will continue to build for the future by providing these young lads with first-team experience, which can only be good for them and the future of Derbyshire cricket."
Welch wasted no time in giving youth its chance - Groenewald was dropped from the squad to face Leicestershire, with Taylor taking his place.