The cancer-stricken beauty, 71, and Travolta, 65, donned their 1950s' style Sandy and Danny duds for a Meet n’ Grease sing-along event at the Coral Sky Amphitheater in West Palm Beach, Florida on Friday, December 13.
“First time in costume since we made the movie! So excited!” Olivia wrote on Instagram.
The Saturday Night Fever actor also had fun with fans over their reunion on social media, writing, “Grease is still the word!”
As RadarOnline.com's photos show, the two friends were delighted to see each other again.
Olivia has previously told Closer Weekly that they stayed close after going "through something as powerful as ‘Grease!’ How can you not, right?”
The blonde star has gushed about John, “He’s a lovely guy. He’s a very loving father, he’s a great husband and he’s a wonderful actor."
Sadly, as RadarOnline.com readers know, Olivia is in the battle of her life during a third bout with breast cancer.
Is she enjoying the trip down Grease's memory lane during her final days?
The beloved "Let's Get Physical" singer was rocked by a devastating stage 4 diagnosis in 2017 after beating breast cancer twice-- in 1992 and 2013.
But she's maintaining her typically sunny attitude: "If you believe the statistics, you’re going to make them happen. If somebody tells you, ‘You have six months to live,’ it’s very possibly you will because you believe that," she said.
“So for me, psychologically, it’s better not to have any ideas of what to expect.”
But Dr. Jonathan Cebon, of Australia’s Olivia Newton-John Cancer Research Institute, has acknowledged, “Stage 4 breast cancer’s not something we see as a curable disease.”
Olivia has said the cannabis grown by her husband, John Easterling, has given her pain relief.
She's inseparable with her only child Chloe Lattanzi, 33.
“They talk every day and are now more like sisters!” a source told Radar.
“Olivia knows she’s incurable — but she’s doing everything she can to make the best of the time she has left.”
That clearly includes hanging out with her former co-star John!
“She’s doing great, and she looks fantastic” John told Us Weekly at the Los Angeles premiere of The Fanatic, on August 22. “I’m so proud of her. I mean, have you ever seen anyone look like that?”
“We text each other all the time. It’s wonderful. … If I go to see her in her show, we go backstage and hang out, and I watch the show and all that. If I go to see her personally, we usually have dinner and catch up.”
Scroll through Radar's gallery for more on Olivia and John revisiting Grease!
Olivia and John, who played lovebirds Sandy and Danny in the iconic 1978 musical, donned a number of different looks inspired by their Grease costumes.
The two, who were huge stars in the 1970s, did a Q&A with fans.
Just last month, Newton-John auctioned off the actual leather jacket she wore in Grease to raise money for cancer research amid her own health battle.
Fans hung on Olivia and John's every word during the event.
In September, Newton-John told CBS This Morning about fighting cancer, "I'm happy. I’m lucky. I’m grateful. I have much to live for. And I intend to keep on living it.”
Olivia sang "Hopelessly Devoted to You," and John warbled "Sandy," and joined a male chorus in "Greased Lightenin'."
Movie fans couldn't help feeling emotional watching Olivia and John together again.
Followers are hoping and praying that Olivia can beat breast cancer yet again. It's clear John is just one of her many loved ones right by her side.
Basking In Love
Grease was one of the most successful musicals of all time.