Dylan Hartley has been ruled out of the remainder of the season including England's summer tour to South Africa due to concussion.
The Northampton captain has not played since the final match of the NatWest 6 Nations against Ireland at Twickenham and it has been decided he should receive an extended break lasting until pre-season for the 2018-19 campaign.
"I'm very disappointed that I will not be available for selection for Saints' remaining Premiership games, as well England's tour to South Africa," Hartley said.
Two years ago Hartley was ruled out for 14 weeks because of two separate concussions, the last in the Grand Slam-clinching victory over France in Paris.
The 32-year-old, an ever-present as captain under Eddie Jones, later conceded he had no memory of the trophy presentation held on the pitch and questioned whether another significant head knock would force him to reconsider his future in the game.
"It has been recommended by specialists that I take a break this summer and while I find that decision hard to accept, it's important I listen to that advice," Hartley said.
"I intend to use this time to recover fully from my injury, so I can be ready to hit the ground running when pre-season training starts later this summer."