The letters contain around 40 drawings.
Previously unpublished letters written by artist Rene Magritte are set to go under the hammer with an antiques valuation of between $150,000 (£93,113) and $250,000.
The documents - which come complete with around 40 drawings - will be sold at Sotheby's in New York, the Guardian reports.
According to the auction house, the items are rare and they suggest the artist was as worried about how his paintings were marketed as the content of them.
Marsha Malinowski, Sotheby's book and manuscripts expert, said the pieces are extraordinary, adding: "Magritte letters are just very hard to find and to have them with so many drawings of his iconic images is extremely rare."
This comes after an antiques valuation of £120,000 was placed on a letter written by John Keats in 1820 to his neighbour Fanny Brawne, the publication revealed.
The item is set to go up for auction at Bonhams in March.
Posted by Keith Leicester