Mars One, the non-profit organization spearheading the project, says the six Canadians include four people from Ontario and two from British Columbia.
A seventh Canadian, a 29-year-old man from the Yukon, who was also selected, dropped out for personal reasons.
The organization says the four women and two men are among a group of about 100 from which they will select a final 24 people to man the missions.
One year ago, 75 Canadians were selected from more than 202,000 who applied in 2012.
Mars One says the mission will cost about $6 billion and says it can be done using existing technology.
But engineers at Boston-based MIT, who analyzed the feasibility of the mission last year, suggest they'll need new technology to keep humans alive once they get there.
One Canadian space scientist has also questioned of the ethics of what Mars One is proposing.
According to Mars One, the Canadians who remain in the running include:
— Daniel Benjamin Criger, 28, Waterloo Ont.
— Karen Louise Cumming, 53, Burlington Ont.
— Reginald George Foulds, 60, Toronto.
— Andreea Lavinia Radulescu, 33, Toronto.
— Joanna Marjorie Hindle, 42 Whistler, B.C.
— Susan Higashio Weinreich, 42, Vancouver.
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