The big event gets under way in Cardiff on Friday night when Wales play host to England.
The reigning European champions Ireland get their campaign under way in Rome on Saturday. Team has just been selected:
15 Rob Kearney, 14 Tommy Bowe, 13 Jared Payne, 12 Robbie Henshaw, 11 Simon Zebo, 10 Ian Keatley, 9 Conor Murray, 8 Jordi Murphy, 7 Sean O’Brien, 6 Peter O’Mahony, 5 Paul O’Connell (captain), 4 Devin Toner, 3 Mike Ross, 2 Rory Best, 1 Jack McGrath.
Replacements: 16 Sean Cronin, 17 James Cronin, 18 Marty Moore, 19 Iain Henderson, 20 Tommy O’Donnell, 21 Isaac Boss, 22 Ian Madigan, 23 Felix Jones.