Runners will chase a Yeti across snow-covered fields near Harborough on Sunday.
The Avalanche Run at Wrongs Farm in Sibbertoft will see about 300 people tackling a tough 10km course, during which they will be challenged to catch the Yeti, who will be get a head-start.
Organisers are bringing in two lorry-loads of real snow to give the start a wintry feel.
Spectators are being encouraged to go along to cheer the runners on.
There will be a DJ and refreshments on offer.
The event will raise money for the Air Ambulance.
For more information visit www.avalancherun.co.uk.