Kate McCann is taking part in a charity run to raise money to help find missing people.
The mother of Madeleine McCann will join other families whose loved ones vanished at the 10km Miles for Missing People, being run in London's Hyde Park on Saturday.
Also attending the event, in aid of the charity Missing People, will be Rachel Elias, sister of former Manic Street Preachers guitarist Richey Edwards, who went missing in 1995, and Nicki Durbin, whose son Luke disappeared in 2006.
Mrs McCann (42) and her husband Gerry (41) from Rothley, Leicestershire, were on holiday with their three children in Praia da Luz in Portugal when three-year-old Madeleine went missing in May 2007.
She said: "I'm running the Miles for Missing People for all missing children.
"Gerry and I know the pain that having Madeleine missing has caused us, but sadly we are not alone. There are thousands of families across the UK waiting for news.
"That's why Missing People provides support for missing children, vulnerable adults and families left behind, and we want to do all we can to help them."
Mrs McCann is raising funds for her run at uk.virginmoneygiving.com/katemccann1.