Former England international Mouritz Botha has retired from professional rugby at the age of 35, on medical advice related to concussion.
The second row played 14 Premiership games in his two seasons with Newcastle Falcons, having moved from Super Rugby side Sharks in August 2015.
"I was truly blessed to have enjoyed my time as a rugby player," Botha said.
In addition to international honours with England, Botha was a Premiership winner in 2011 in a highlight of six seasons and 142 games at Saracens, while he began his career in England with Bedford.
"I am extremely proud to have been able to represent England, an honour that I will always cherish, and to have won the Premiership with Saracens," Botha added.
Falcons director of rugby Dean Richards added: "It is sad when any player is forced to retire in this manner, but Mo can look back on a great career which has seen him winning the Premiership title and playing international rugby for England."