This year's Baxters Loch Ness Marathon and Festival of Running will have a new event that will seek to find Scotland's fastest clan.
People with surnames such as Cameron, Campbell, Macleod, Macdonald and Macrae are being invited to take part in the marathon and River Ness 10k.
The Clan Challenge will be held as part of the Year of Homecoming Scotland 2014.
The marathon and festival of running takes place on 28 September.
The events are held on roads near Loch Ness, the River Ness and Inverness.
Race director Malcolm Sutherland said he hoped entrants will wear a piece of their clans' tartan on the runs.
He said: "We are urging Scots at home and abroad or anyone with an affinity to Scotland to come and help push their clan to victory.
"Last year we had runners from all over the UK and 30 different countries participate in the Loch Ness Marathon and Festival of Running, and we hope that the Clan Challenge will see even greater numbers come forward this year."
The race programme includes the marathon, River Ness 10k, a 10k corporate challenge, 5k and the Wee Nessie run for children.
Finance Secretary John Swinney said the events offered people a chance to enjoy "beautiful scenery".
He added: "The marathon will also celebrate Scottish ancestry, with Scots from home and abroad to represent their family in the Clan Challenge.
"The Year of Homecoming in 2014 is a unique opportunity to encourage more visitors, both international and domestic to come and enjoy Scotland."
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