The appellation, named after the small town of the same name, is located in the east of the wine growing region of south-west France. Gaillac is one of the oldest wine-growing regions in France. At least since the 1st century the Romans have been growing wine here. It is possible, however, that there had already been winegrowing under the Celts (Gauls) before that. During the migration of the peoples it came to a standstill and was only reestablished in the 10th century by the Benedictine monks of the monastery Saint-Michel-de-Gaillac. In the 13th century, the Count of Toulouse Raymond VII issued a decree for his wine region for a controlled designation of origin. Already in the 12th century, wine was exported to northern Europe, especially to England, where it enjoyed great popularity. The Aquitanian poet Auger Galhard (1540-1593) praised the sparkling wine long before the invention of champagne. Until the middle of the 20th century, the company specialised in sweet white wines, but then it also began to produce rosé and red wines. The trademark is the rooster with three lilies from the Gaillac city coat of arms, which is why the wines used to be called "Vins du Coq".
The vineyards cover some 3,500 hectares of vineyards north of the city of Toulouse in the department of in the valley of the Glecihnamigen river. This is just over a third of the 9,000 hectares of vineyards in the département. The area is divided into the lower slopes with loamy-calcareous soils, the higher elevations of the Cordes plateau on highly calcareous soils of the right bank, and the gravel-sand zones of the left bank of the Tarn. The Gaillac area has very special climatic conditions. The climate is neither Mediterranean nor Atlantic, but more continental. Summers are hot and dry, with rainfall mainly between September and April. Another special feature is the warm east wind Autan.
The naturally sweet white wines are marketed under the Gaillac Doux appellation (the appellation names Gaillac Liquoreux and Gaillac Moelleux, which were previously used for it, are no longer permitted). These must have at least 70 g/l residual sugar. Under the appellation Gaillac Prèmieres Côtes, mainly dry but also sweet white wines from 11 municipalities on designated limestone slopes are produced. The former Gaillac Sec Perlé for slightly sparkling wines has been discontinued. For sparkling wines some appellations have been created according to the production method (see also Méthode rurale).
A speciality are the lightly sparkling wines in white and rosé produced under the designation Gaillac Mousseux Méthode Gaillacoise. The wines undergo only a single fermentation. There is also the sweet version Gaillac Mousseux Méthode Gaillacoise Doux with at least 45 g/l residual sugar. Under the designation Gaillac Mousseux Méthode Deuxième Fermentation, sparkling wines in white and rosé are produced according to the Champagne method. Another speciality is the "Vin de Voile" (voile = veil), which is produced in the manner of a Vin Jaune. The name is derived from the fine layer of yeast in the wine.
The Gaillac wines are bottled in the special bottle shape "Gaillacoise". Since vintage 2004 there is a uniform shape (middle bottle), which is a compromise between the shorter red wine bottle (right) and the slimmer white wine bottle (left). Well known producers are Domaine des Bouscaillous, Château de Branes, Domaine Jean Cros, Château d'Escabes, Domaine de Labarthe, CV de Labastide-de-Levis, Château Montels, Domaine du Moulin, Domaine de Rieux, Domaine Rotier, Domaine des Terrisses and Domaine de Vayssette.