The race will be entirely made up of the wives of serving soldiers in The Royal Highland Fusiliers, 2nd Battalion The Royal Regiment of Scotland (2 SCOTS).
The first of 14 shuttles will start from the castle esplanade at 9am, each wife will travel the full distance between the castle and the Scottish Parliament and back again.
The money they raise through sponsorship will be given to the white hackle charity appeal which provides support for injured soldiers and their families.
Captain Walter Barrie, Unit Welfare Officer at 2 SCOTS said: “The troops from 2 SCOTS who are normally based at Glencorse Barracks, Penicuik, are currently deployed in Afghanistan, and are approximately half-way through their tour of duty in Helmand Province.
“The Royal Mile Relay is a great opportunity for the wives to focus on something in support of their husbands and raise awareness of our wristband appeal.”
Jane Strudwick, wife of Major Piers Strudwick who is currently serving in Afghanistan explained:
“The ladies taking part in The Royal Mile Relay have been training hard over the past couple of months and are looking forward to taking part in this, the next challenge to raise money and awareness for our charity www.whitehackle.com.
“It has been a great way to improve fitness, help time go by quickly and support our husbands while they are away in Afghanistan serving with 2 SCOTS.
She continued: “With 2011 here we can begin to think about the return of our loved ones and this event helps us remain committed to supporting them and ourselves during this prolonged time of separation.
“We are hugely grateful to all the support that we have received from the public and local businesses, thank you!”
Mrs Strudwick added: “Good Luck to all those taking part on Saturday and I ask members of the public to give them lots of encouragement as they run up and down the Royal Mile.”