The ABA contents in the berries of Muller Thurgau and Silvaner vines were studied from July to early November during 2 growing seasons. The absolute contents ( mu g/1000 berries or seeds) and the concentration ( mu g/kg) of ABA increased in seeds and pulp to a maximum at the beginning of phase IV of berry development (in September and October) and decreased thereafter. The decrease of ABA could not be attributed to the effects of a short frost period.