The Six Nations championship is to be condensed into a seven-week tournament from 2003.
The decision was made by the Six Nations committee in Paris, despite objections from the Welsh Rugby Union.
The move alters the traditional structure of Europe's premier competition, which had seen matches played every other weekend.
The move will be greeted with joy by most members of the rugby community, particularly the players who feel the constant switch from club combat to the international arena doesn't help their preparation.
Officials were also aware of the need to shorten the duration of the competition in order for it to gather greater momentum and make it more attractive to prospective bidders for television contracts.
"The committee were acutely aware of the challenge of making any significant change to the format of the world's most successful annual competition, and great concern was expressed as to the implications for rugby supporters," said Six Nations committee chairman Allan Hosie.