Barley wine or Barleywine is a style of strong ale originating in England in the nineteenth century (derived from the March or October beers of the 18th century) but now brewed worldwide. The term was originally coined around 1900 by Bass to refer to their No. 1 Ale. It is the strongest member of the bitter family of styles.

It typically reaches an alcohol strength of 8 to 12% by volume and is brewed from specific gravities as high as 1.120. It is called a barley wine because it can be as strong as wine; but since it is made from grain rather than fruit, it is in fact a beer. In the United States barley wines are required for this reason to be called "barley wine-style ales." This is taken by some to imply that they are not truly barley wines; in fact it only means that they, like any barley wines, are not truly wines.

Their natural sweetness is usually balanced with a degree of hoppy bitterness. The flavor of ethanol may also be present in some examples.

This beer is meant for slow sipping and savoring of its estery, fruity, and well-aged character. It is brewed most often to celebrate events. Because of the high hop rate and alcohol content, some barley wines are aged for years.

Most barley wines range in colour from ambers to deep reddish-browns.