England Lions paceman Tymal Mills is to leave Essex when his contract expires this winter.
Mills, 22, played only 12 games this summer because of a back injury, and retired hurt on his last One-Day Cup appearance against Hampshire in August.
Essex had offered the left-armer a new contract to stay at Chelmsford but he rejected the deal.
Meanwhile, spinner Tim Phillips has retired at the age of 33 after 16 seasons with the county.
Mills, who regularly bowls at over 90mph, spent last winter with the England Performance squad and was drafted into the senior side's Ashes training camp to provide the batsmen with practice against left-arm pace bowling.
But he took only 13 wickets at an average of 34 for Essex in his six County Championship Division Two outings this season, and six more in four T20 Blast matches.
Essex head coach Paul Grayson said: "We are of course disappointed that Tymal has decided to leave the club, especially as he is one of our own from the Essex academy.
"There was an attractive new contract offer on the table for him but he has decided to reject and continue his career with a new club."
Mills added: "It is with a heavy heart that I have decided to leave Essex. I want to thank the club for giving me my introduction into professional cricket.
"I am excited for the next chapter in my career and wish the club all the best moving forward."
Confirmation of his departure follows that of Cambridge-born Phillips, who made 78 first-class appearances since his debut for Essex in 1999, taking 132 wickets.
He averaged 26.80 and 26.18 with the ball in one-day and T20 matches respectively, and scored 2,779 runs across all formats.
"I have enjoyed my career and the friendships I have made during my 16 years representing Essex," said Phillips.
"I would like to take this opportunity to wish the club all the best for the future."
Grayson said: "Tim has been a very loyal member of our squad over the years, and was a key part of our successful one-day teams.
"I would like to thank him for all his years of service, and wish him the best for the future."