A style of Belgian beer, made by fermenting lambic with sour Morello cherries (kriek is the Flemish word for this type of cherry).

Traditionally, kriek is made by breweries in and around Brussels using lambic beer to which sour cherries (with the pits) are added. A lambic is a sour and dry Belgian beer, fermented spontaneously with airborne yeast said to be native to Brussels. The presence of cherries (or raspberries) predates the almost universal use of hops as a flavouring in beer. A traditional kriek made from a lambic base beer is sour and dry as well. The cherries are left in for a period of several months, causing a refermentation of the additional sugar. Typically no sugar will be left so there will be a fruit flavour without sweetness. There will be a further maturation process after the cherries are removed.

More recently, some lambic brewers have added sugar to the final product of their fruit beers, in order to make them less intense and more approachable to a wider audience. They also use cherry juice rather than whole cherries and are matured for much shorter periods.