Dave Wilson has been on a kidney transplant waitlist for four years. Now he's recovering from a successful transplant, thanks to a donor he found after placing an ad online.

His wife Lois placed an ad on Craigslist out of desperation when she realized she wasn't a match.

"I'm willing to donate my kidney to someone else out there who needs it, if they have a partner who's willing to donate their kidney for my husband," Lois told CTV News.

Publicity surrounding the ad finally helped Dave find a donor. Of 30 people who came forward, a complete stranger ended up being a perfect match.

What's he getting out of it?

"The satisfaction," Lois said. "He said, ‘I can donate it because I have two.'"

For Dave, this means a chance at freedom from the four hours each day, three days a week, that he spends hooked up to a kidney dialysis machine.

The Wilsons say no money was ever exchanged, and Lois didn't have to give up her kidney in a trade.

But the donation is still highly controversial.

Dr. Paul Keown, Director of Immunology at Vancouver General Hospital, says cases like this might be problematic for the kidney donor system.

"It creates competition between patients on the list when we have multiple personal appeals for organs, and it really undermines the whole structure of the waiting list," he said.

Anita Ho of the UBC Centre for Applied Ethics said placing an ad raises ethical questions, too.

"When we're talking about putting up a private ad, there's very little checks and balances happening in the private realm, so some people might worry that now kidneys can become a commodity," she said.

There's already a paired exchange registry that sets up the kind of donations the Wilsons sought on Craigslist.

As for the mysterious kidney donor, he's asked not to be identified.

"I just think he's the most wonderful man. He's my hero, and it's too bad in a way that he wants to remain anonymous," Lois said.

With a report from CTV British Columbia's Michele Brunoro