Organic wine is wine made from grapes grown in accordance with principles of organic farming, which typically excludes the use of artificial chemical fertilizers, pesticides, fungicides and herbicides.The legal definition of organic wine varies from country to country.The primary difference in the way that organic wine is defined relates to the use (or non use) of preservatives during the wine-making process.

Wine production comprises two main phases - that which takes place in the vineyard (i.e. grape growing) and that which takes place in the winery (i.e. fermentation of the grapes into wine, bottling etc.). The baseline definition of organic wine as "wine made with grapes farmed organically", deals only with the first phase (grape growing). There are numerous potential inputs which can be made during the second phase of production in order to ferment and preserve the wine. The most universal wine preservative is sulphur dioxide. The issue of wine preservation is central to the discussion of how organic wine is defined.

Wine matures over time, and it is widely considered that certain types of wines improve with aging, as the flavors become more integrated and balanced. As a result, the greatest percentage of wines are produced in a way that allows them to last, sometimes as long as decades. The use of added sulfites is debated heavily within the organic winemaking community. Many vintners favor their use in small quantities for stabilization of wine, while others frown on them. Currently the only effective preservatives that allow wines to last for a long period are 'non-organic'. While there are a growing number of producers making wine without added preservatives, it is generally acknowledged that these wines are for consumption within a few years of bottling.

The various legal definitions of organic wine serve to address this challenge regarding the use of preservatives. In some parts of the world, namely Europe, wine cannot legally be labelled as 'Organic Wine'. Wines that have added sulfites, but are otherwise organic, are labeled "wine made from organic grapes.". In the United States, wines certified "organic" under the National Organic Program cannot contain added sulfites.

In the USA, strict rules govern the organic winemaking process at all stages of production including harvesting, the types of yeast that can be used during fermentation as well as storage conditions. These rules are applied for all imported and domestic wines that acquire USDA certification. In the USA, the total sulfite level must be less than 20 parts per million in order to receive organic certification. Organic certification in the UK is more simple as based on the fact that the grapes are grown organically.

Organic certification of wine is complex; different nations have different certification criteria. In the United States, the National Organic Program, run by the United States Department of Agriculture, sets standards for certification of organic foods, including organic wines.In the United Kingdom, organic wine is defined as such made out of organic grapes.Some wineries that are technically organic choose not to be certified for various reasons.