An estimated 6,000 runners and walkers laced up for the Canadian Breast Cancer Foundation Fundraiser, many in teams and brightly coloured costumes.
Linda Larin and Donna Babin took part with team Bosom, Biddies and Babes.
"It's a long journey. It's a hard journey," said Linda Larin, a breast cancer survivor. "That's what we come for, to encourage the ones who are still working at it and trying to survive."
Last year's run raised roughly $800,000 dollars, with most of the profits staying in the national capital region. More than $20 million has been raised from the Ottawa-Gatineau event alone since it started 23 years ago.
"The money goes to amazing research and every day that I had treatment, I was overwhelmed with emotion to know I was blessed to be receiving that treatment," said Donna Babin.
For many participants, the event is a chance to stand together with other survivors and to remember those who lost their battle.
Marcie Martel was diagnosed earlier this year and walked in Sunday's 1 km with about 100 friends, family and colleagues.
"It's nice to know that I'm not alone because there are so many people here," Martel said. "It's kind of sad to see how many people have been affected. I don't know, it's overwhelming."
More than 100,000 people take part in the CIBC Run for the Cure every October. The event happens in more than 63 communities across the country.