The Hawke's Bay leaper, who was a surprise inclusion in this year's national squad, will undergo surgery on his back and is out of rugby "for the foreseeable future", according to All Blacks doctor Deb Robinson.
Evans was forced to withdraw from the Hawke's Bay team ahead of their Air New Zealand Cup match against Wellington last weekend after suffering back pain while training.
Robinson said Evans had been diagnosed with a small disc prolapse in his back after undergoing a scan and seen a specialist this week.
Robinson said it was too early to tell just how long Evans would be out of rugby.
"It's a case of him having his surgery and recovering from that first. Then he will go through his rehabilitation and we will take it from there," she said.
The 24-year-old joins a group of All Blacks players who will struggle to return to the rugby field this year, including lock Ali Williams, hooker Keven Mealamu and centre Richard Kahui.
Evans, who struggled to make the Hurricanes starting team during the Super 14, was named as a standby player for the All Blacks for their June home tests.
His "core strengths" of lineout and kickoff receipts were cited as his strength by the national selectors.
He made his debut off the reserve bench in the two home tests against France but wasn't selected for the 22 in any of New Zealand's first three Tri-Nations tests.
All Blacks Coach Graham Henry said it was disappointing time for Evans.
"Bryn is an extremely skilful player and had been making great progress in the All Blacks environment and we will be supporting him as he goes through his rehabilitation," Henry said.
