Yorkshire Carnegie captain and former England player Chris Jones has retired after suffering concussion last month.
The 35-year-old, who played as lock and flanker, made his England debut in the 2004 Six Nations and picked up 12 caps.
He made 40 appearances for Carnegie before suffering concussion against Nottingham in April.
"Having spoken with the club's doctors they have advised me that it would not be safe for me to continue playing," Jones said in a statement.
"Since the Nottingham game I have experienced a number of side effects from the concussion and I am now working with the Industry of Sport in London on treatment.
"I joined Yorkshire Carnegie with the ambition to get the club promoted and am gutted that I am having to call time on my career."
Jones' England career began in 2004 where he played against Scotland and Italy in the Six Nations, before starting against the All Blacks in that year's tour.
He played for Sale Sharks for 10 years, helping them to the Premiership and European Challenge Cup, before joining Carnegie from Worcester Warriors in 2014.
"This is a tough way to end a playing career but head injuries are not to mess about with," Carnegie coach Bryan Redpath said.
"It has been a great pleasure, firstly playing alongside him to then getting the opportunity to coach him. On behalf of the club we wish him well on new challenges ahead."