McBryde, who missed two of the Six Nations games through injury, has been told that he will almost certainly require an operation on his troubled shoulder.
The British Lion front-rower has been omitted from Llanelli's team to face Leinster in tomorrow night but it is hoped he will play some part in the run-in for the Celtic League title.
"We though it was best to him for this game though we know that Robin will need an operation at the end of the season to correct the problem which
will probably rule him out of the summer tour," said Scarlets coach Nigel Davies.
"Robin has seen a consultant and he can play but he is not able to maintain his conditioning, but we have taken the view that because these next four games are so hugely important to our season, he will play and the operation will come after that period."
The news will come as a huge disappointment for new Wales coach Mike Ruddock who would dearly love to have a powerful player of McBryde's experience at his disposal for the tough-looking Tests in Argentina on June 12 and 19 and South Africa on June 26.
Star lock Robert Sidoli has already pulled out of the tour in order to rest an on-going pelvic problem that forced him to miss more than half of the Six Nations.
"He needs an injection and complete rest to overcome what has been a recurring problem," said Warriors coach Lynn Howells.