Barry has won 39 caps for the Springboks

Barry, who has won 39 Test caps, will move to the London club from Western Province in October.

"I am sure I will be very happy at Harlequins and intend on making the most of this opportunity," said Barry.

Quins boss Dean Richards said: "He's a formidable defender and a fantastic runner so I expect him to fit into the Guinness Premiership with ease."

Barry, who also plays for the Super 14 side the Stormers, said he was sorry to be leaving Western Province.

"I have thoroughly enjoyed my time and the set up at Western Province. It is a great environment to play rugby in and I have formed solid friendships over the years which I will carry through with me in my life," he said.

"Western Province is a union with a great history and it has been an honour to represent them over the years.

"I was fortunate to play for the Springboks and felt a great sense of pride to represent South Africa.

"I am looking forward to the challenge of joining Harlequins and look forward to the new chapter in my rugby career.