Marsanne () is a white wine grape, most commonly found in the Northern Rhône region. It is often blended with Roussanne. In Savoie the grape is known as grosse roussette. Outside France it is also grown in Switzerland (where it is known as ermitage blanc or just ermitage), Spain (where it is known as Marsana) It can be found in some white wines from the Côtes du Rhône AOC. Although Marsanne is mostly made into a dry wine, it is commonly made into a sweet wine in Valais, Switzerland and some producers in the Rhône have also experimented with making a dessert-style straw wine with Marsanne.
Outside the Northern Rhône region, Marsanne is also found in Savoie and in the Languedoc where it is often blended with Viognier. Varietal Marsanne from Washington has been shown to have notes of ripe white peach and spiced pear. In California, the Rhone Rangers movement introduced Marsanne to more consumers in wines that are often blended with Roussanne and Viognier. In Spain there are some plantings of Marsanne in the northeast. In nearby Hastings Marsanne is blended with Viognier and fermented in aged French oak barrels which give a richness and complexity without introducing intrusive oak notes.
Viticulture
thumb|right|Leaves of Marsanne vines.
While not as temperamental as the Roussanne grape, Marsanne is prone to underperform in less than ideal sites. In climates that are too hot, the grape can overripen and produce wine that is very flabby. In places that are too cool, the grape cannot ripen fully and produces wine with a bland and neutral flavor. In order to maintain a high level of acidity, winemakers try to harvest Marsanne just before it hits full ripeness. Some Australian winemakers prefer to let the grape hang longer on the vine to increase the alcohol level of the wine and its aging potential.