Sémillon is a golden-skinned grape used to make white wines, most notably in Bordeaux and Australia.

The principal use of Sémillon is in the great wines of Sauternes and Barsac where it is used with Sauvignon Blanc to produce what are generally accepted to be the finest sweet wines in the world. In such wines, the Sémillon is attacked by the "noble rot" of Botrytis cinerea which consumes the water and thus concentrates the sugar ready for picking. It is also used in the nearby region of Pessac-Léognan to make a dry white wine, adding maybe 10 or 20 percent Sémillon to Sauvignon Blanc.

When used to make wines on its own, Sémillon has almost always disappointed, producing a dull, tasteless drink that is only really good for distilling to brandy. Even in Sauternes its usage is only assured by the intervention of the botrytis fungus. It is thus almost always used in blends.

The other wine making region that has assured Sémillon's fame is Australia, where Sémillon Chardonnay blends have proved extremely popular around the world. In addition, in the Hunter Valley north of Sydney, a region otherwise totally unsuited to wine making, the grape is used to make the Hunter Valley Semillon which occasionally matures extremely well to become one of the world's great white wines.

Due to its lack of flavour, the amount of Sémillon grown has decreased hugely over the last century; in the 19th century the grape covered over 90 percent of South Africa's vines (where it was known as Wyndruif – "wine grape"), and Chile's post-war vineyards were made up of over 75 percent Sémillon. Both countries still grow the grape successfully but in vastly reduced quantities as Chardonnay has moved into vogue.