Barsac (French pronunciation: [baʁsak]; Gascon: Barçac) is a commune on the left bank of the Garonne river in the Gironde department in southwestern France.

Barsac is located 37 km upstream the Garonne river of Bordeaux.

Barsac station has rail connections to Langon and Bordeaux.

The town gives its name to a wine making appellation, Barsac AOC, that produces sweet white wines.

The town and its vineyards are separated from the area of Sauternes to the south by the Ciron river, whose cooling effect is of key importance in encouraging the annual action of the Botrytis fungus on the Sémillon grapes.