Tannat is best known as the dominant grape variety in Madiran, Southwest France's most famous red wine. The grape probably originated in the Basque country and almost certainly derives its French name from its high tannin levels. It is a thick-skinned grape variety that produces deeply coloured, well-structured wines that can be tough and austere in youth. However with ageing the massive tannins round out while the wine develops nuances of spices, coffee, cocoa, and vanilla.

In Madiran it is blended (typically 60-70%) with Cabernet Sauvignon, Cabernet Franc, and Fer. The only other country where Tannat is seriously grown is Uruguay, where it was planted by Basque settlers in the 19th century. It is known as Harriague in Uruguay and recently plantings have spread over the border into Argentina.