People from across the Isle of Man will be taking to the streets in their underwear in aid of charity.
Last year the dash raised more than £18,000 for charity
The Bra Walks on Friday are to raise money for the island's branch of Breakthrough Breast Cancer.
This annual event has raised more than £30,000 for the charity in the two years it has taken place.
Hundreds are expected to take part in the races, which are being held in Douglas, Castletown and Ramsey. A fourth is in Peel on Saturday.
Organiser Angela Aired said the mile-long race is good fun with a serious message.
"There are serious runners who try for a fast time but most runners carry buckets and go collecting in pubs shops and cafes along the way," she said.
There are prizes for the best dressed person, best bra and best team as well as trophies for the fastest time.