Nick Blackwell says he will not fight again after sustaining serious head injuries in his British middleweight title loss to Chris Eubank Jr.
Blackwell, 25, was placed in a coma with bleeding in his skull after his 10th-round defeat at London's Wembley Arena on 26 March.
"No that's me done," the Briton tweeted after being asked on the social media site if he would be making a comeback.
"I can't put my friends and family and self through that again."
Blackwell wants to stay in the sport in some capacity and said he holds "no hard feelings" towards Eubank Jr as he continues his recovery.