British and Irish Lions captain Sam Warburton has retired from rugby union at the age of 29, the Welsh Rugby Union and his club Cardiff Blues said.
Flanker Warburton, who won 74 Wales caps and captained his country a record 49 times, was forced to sit out last season after undergoing knee and neck surgery.
"Unfortunately, after a long period of rest and rehabilitation the decision to retire from rugby has been made with my health and well-being as a priority as my body is unable to give me back what I had hoped for on my return to training," Warburton said, picking out Wales coach Warren Gatland for special praise.
"To look back on my career, I'm extremely proud of what I managed to achieve.
"I would like the make special mention of Warren Gatland. Without the faith he had in me and his unwavering support I would never have had the career I was able to pursue."
Warburton, who spent his entire professional career with Cardiff Blues, making his debut for his hometown region in April 2009 and winning his first cap just two months later, will go down in history as the most successful British and Irish Lions captains of all time.
Last year he became only the second man after ex-England lock Martin Johnson to captain the Lions on two tours as he led the touring team to New Zealand, repeating the honour he first undertook in 2013 in Australia.
Under his leadership the Lions claimed a first Test series victory in 16 years when they beat Australia and four years later in 2017 he once again led the Lions as they earned an historic series draw against double defending world champions New Zealand.
Wales coach Gatland, who led the Lions on their last tour to New Zealand, added: "It is hugely disappointing that Sam has retired from the game. He is an outstanding rugby player and he has brought so much to the game on and off the pitch.
"His leadership, attitude and demeanor along with his performances have placed Sam up there as one of the best and most respected players in the world. He finishes with a record that he should be extremely proud of and should look back on his career with huge pride."
The Welsh Rugby Union and Blues issued a joint statement which said: "Since returning to pre-season with Cardiff Blues, it has become clear to Warburton that he wouldn't be able to return to the high standards he has set throughout his career and has reluctantly made the decision to retire."