Foley missed the Waratahs' first four games before returning to face the Melbourne Rebels two weeks ago. However, the symptoms reappeared and he missed last Sunday's 41-22 loss to the Canterbury Crusaders.
"Bernard has been given the clearance after further expert reviews, including a review with neurologist, and treatment over the course of the last week," Waratahs coach Daryl Gibson said in a statement on Wednesday.
Foley's fellow Wallabies back Rob Horne has been withdrawn from the side due to a hamstring injury after initially being named to start in the centres. Israel Folau, therefore, returns to the number 13 jersey with Bryce Hegarty in at fullback.
Hulking winger Taqele Naiyaravoro has also earned his first start of the season after a barnstorming performance against the Crusaders when he ran over the top of George Bridge to score.
There will be no clash of giants on the wing, however, as the Hurricanes' Julian Savea has been rested for Friday's match at Wellington Regional Stadium.
Vince Aso, the competition's top try-scorer with seven, has also been rested, allowing Cory Jane to make his first appearance this season while Wes Goosen gets his first start.
"If you look at Julian and Vince, they've both started all five matches so far, so its a chance for them to freshen up, but equally it gives Cory and Wes an opportunity," Hurricanes' coach Chris Boyd said.
"At the end of the day we have faith in the depth in our squad, so whoever runs out there were confident they'll do the job. It's a long season and you need to utilise your whole squad."
The Hurricanes will again be without All Blacks hooker Dane Coles, who has failed to recover from a knee injury.
Loose forward Ardie Savea was not considered after he sustained a calf injury in their 34-15 win over the Queensland Reds.
The Hurricanes, last year's winners, are looming again as one of the competition favourites and have 20 points from five matches.
The Waratahs have just eight points after six games but have the benefit of playing in a poorly-performing Australian conference and remain in the playoff hunt, though they must start picking up points to stay in contention.
(Reporting by Greg Stutchbury; Editing by Peter Rutherford)
