During the classical period, wine was so often adulterated and counterfeited that Pliny the Elder complained that not even the nobility could be assured that their wine was genuine.

Wine fraud may come in several forms. In all cases the fraud relates to the commercial aspects of wine. The most prevalent type of fraud is one where wines are adulterated, usually with the addition of cheaper products (e.g. juices) and sometimes with harmful chemicals and sweeteners (compensating for colour or flavour). Counterfeiting and the relabelling of inferior and cheaper wines to more expensive brands is another common type of wine fraud. A third category of wine fraud relates to the wine investment industry. This often works by offering wines to investors at excessively high prices. In some cases the wine is never bought for the investor. Losses in the UK have been high, prompting the DTI and Police to act. In the US, investors have been duped by fraudulent wine investment firms too. Independent guidelines to potential wine investors are now available.

In wine production, as wine is technically defined as fermented grape juice, the term "wine fraud" can be used to describe the adulteration of wine by substances that are not related to grapes. In the retailing of wine, as wine is comparable with any other commodity, the term "wine fraud" can be used to describe the mis-selling of wine (either as an investment or in its deceitful misrepresentation) in general.

For as long as wine has been made, wine has been manipulated, adulterated and counterfeited. In ancient Rome, Pliny the Elder complained about the abundance of fraudulent Roman wine which was so great that even the nobility could not be assured that the wine they were pouring on their table was genuine. For the poor and middle class of Rome, local bar establishments seemed to have an unlimited supply of the prestigious Falernian wine for unusually low prices.

Over the years, winemaking techniques have evolved. The first, primitive "natural wine" or "authentic wine" was most likely the result of crushed grapes being forgotten while stored in a container. The process of allowing wild yeast found on the surface of the grape conduct fermentation in an uncontrolled environment creates a very crude style of wine that may not be palatable to many people. Hence the development of various techniques and practices designed to improve the quality of the wine but which could be viewed as "manipulating" or "adulterating" the wine from its natural or "authentic state". At various points in history, these technique may be considered too much manipulation, more than what a consumer would likely expect, and thus labeled as "fraud". However as these techniques became more common place in the wine industry, an air of acceptability followed and they eventually became just another tool in the winemaker's tool box to help craft quality wine.

In 1985, diethylene glycol appeared to have been added as an adulterant by some Austrian producers of white wines to make them sweeter and upgrade the dry wines to sweet wines; production of sweet wines is expensive and addition of sugar is easy to detect. Fortunately, the amount added was not high enough to be toxic except at impossibly high (for most people) levels of consumption (one would have needed to ingest about 28 bottles per day for approximately two weeks in order to suffer fatal effects). Twenty-three people died in 1986 because a fraudulent winemaker in Italy blended toxic methanol (wood alcohol) into his low-alcohol wine to increase its alcohol content.

See also:
Wine Fraud