The Royal Bank of Scotland Group has been title sponsors of the Six Nations Championship since 2003. Since then, the Championship has grown to become the world's best attended rugby event.
The Championship's matches are also broadcast on television in more than 160 countries around the world and viewing figures have increased by over 30% in the last decade.
The partnership has benefited the game of rugby at its grassroots, through the RBS RugbyForce programme, which has supported more than 1,000 clubs and their communities since its launch in 2009.
John Feehan, Chief Executive of Six Nations Rugby Ltd, said: "We are delighted to extend our successful partnership with RBS.
"In the 11 years that the bank has backed the Championship we have worked together to exponentially grow the tournament both at a global level in terms of fans enjoying the games, but also at a community level, through the RBS RugbyForce programme."
Gregory Thorpe, head of brand and marketing at RBS, said: "Our RBS 6 Nations sponsorship delivers significant value to our business and is the cornerstone of everything we do in rugby. The Championship is a source of pride and passion for many of our customers, from the living room to the board room.
"Our involvement helps us engage more effectively with those customers and to connect with the communities in which we operate. We're thrilled to be on board for another four years."