One of the most anticipated items up for auction are Sandy's black leather jacket and skin-tight pants from the final scenes of Grease.
"The jacket we're estimating $100,000 - $200,000; the pants we estimate $40,000 - $60,000," Julien's Auctions Executive Director Martin Nolan told Weekend Sunrise.
"(They are) conservative auction estimates because, truly, this is the one everyone wants ... it's going to be one for the record books"
All the proceeds from the jacket and pants, and a portion from the rest of the items will go towards Newton-John's Wellness and Research Centre, a charity set up after her own battles with cancer.
"Olivia's doing really well health-wise and the cancer centre is so important to her," Nolan said.
"She's striving to find a cure for cancer in our lifetime, so this is really personal."
The auction gets underway at 4am Sunday AEDT (10am Saturday in California).