The versatile Purdham was a member of England's World Cup squad
Harlequins captain Rob Purdham has agreed a two-year contract extension that will keep him at the London club until the end of the 2011 season.
The England international has made more than 150 appearances for the club since joining them from Whitehaven in 2002.
"I've always been happy in London and so extending my contract was a no-brainer," said the 29-year-old
"I'm looking forward to helping to cement Harlequins Rugby League as a top Super League club."
Harlequins coach Brian McDermott said: "I cannot stress enough how big a compliment it is to this club, that a player of Rob's calibre and status in the game has chosen to stay with Harlequins.
"Rob has been attracting the attention of other clubs and coaches for a couple of years now and I'm really pleased that he's pledged his future to us."
Quins are currently fourth in the Super League table after winning eight of their first 12 league games this season.