More than 20,000 animals, mostly lambs, have been put up for auction at Lairg.
The sheep are transported to the livestock mart in the small Highlands village from all over the north of Scotland.
Ahead of the sale, United Auctions' chief executive David Leggat said it was hoped better prices would be achieved than last year.
What is regarded to be Europe's largest one-day sale of hill sheep has been taking place in Sutherland.