A Calgary man is receiving a kidney from an unexpected donor -- his childhood playmate.

Gordon Passage and Lily Ahonen first met in elementary school 35 years ago. Now, the two will share a new lifelong bond, through organ donation.

The two told CTV Calgary they did not keep in touch over the years, but Ahonen reached out to Passage when she heard he was experiencing some health issues.

“I saw on Facebook that he was having some health challenges and then was needing a kidney, so, kind of as a joke, I was like, ‘Oh, I'll give you a kidney no problem!’” said Ahonen. “And then we started talking more about it.”

At 35, Passage suffered kidney failure and six years later, he was placed on dialysis.

A family donor wasn’t an option so Passage and Ahonen began testing to see if they really were compatible for a transplant.

When doctors confirmed that they were a match, Ahonen said it wasn’t a difficult decision whether to go through with it.

“[Doctors] said it's pretty rare we were such a good match, such a close match,” she said.

The transplant surgery will take place Thursday, with recovery expected to last six weeks for Ahonen, and at least 12 for Passage.

“It means everything,” said Passage. “…I'll have a piece of her inside me.”

The Kidney Foundation of Canada says approximately half of the kidney transplants that take place are because of living donors.

“There [are] so many people that need a transplant and you can live well with only one kidney if you're deemed to be an eligible donor,” said Joyce Van Deurzen, executive director at The Kidney Foundation of Canada. “You could really change someone's life.”

The foundation says there are currently 4,500 Canadians on the organ donation list waiting for a kidney.