Rob Buchanan has joined fellow Harlequins hooker Dave Ward in committing his future to the Aviva Premiership club.
Buchanan, 24, is a product of the Harlequins academy and has made 82 appearances for the first team while competing with Ward and Joe Gray for the No.2 shirt.
"Rob is the youngest of our three senior hookers but his potential is huge," the club's director of rugby Conor O'Shea said.
"He is tough and abrasive, has improved his set piece massively and his play in the loose is uncompromising.
"Rob has suffered some injuries over the past few years which have stalled his progress but long term, this could have been the best thing that happened him.
"There are real signs that he is back to his best and is ready to kick on."
Buchanan has represented England at age group levels and featured in senior squads under Stuart Lancaster, although he is yet to win a Test cap.
"I'm really pleased to have re-signed and I'm grateful to Conor and the coaching staff for giving me the opportunity to continue at Harlequins," he said.