Scotland scrumhalf Rory Lawson announced on Wednesday that he has been forced to retire because of a chronic wrist injury.
The 32-year-old joined Newcastle from their fellow Premiership side Gloucester last year.
He made his Scotland debut against Australia in 2006 and made a further 30 Test appearancs, captaining his country on five occasions.
"I am obviously gutted to have been forced to stop playing the game I love, but I will always look back on my career with immense pride," Lawson said.
"I am not entirely sure what the future holds at this stage, but there are a few opportunities to explore."
Newcastle Rugby Director Dean Richards said Lawson had been "a magnificent servant to the game" and would be "sorely missed".
"I thank him for his commitment to the club last season in helping us achieve our main objective of Premiership rugby, and I think I speak on behalf of everyone at the club in wishing him all the very best for the future," said Richards.