One hundred twenty-five yeast strains isolated from table grapes and apples were evaluated for the controlBotrytis cinereaof in vitro and in vivo. Ten strains were selected for their ability to inhibit mycelial growth ofB. cinereain vitro. In the in vivo assays, these yeasts were tested at 20 °C on ‘Thompson Seedless’ berries for 7 days; only three were selected (m11, me99 and ca80) because they significantly reduced the incidence of gray mold. These three yeast strains were then evaluated at different concentrations (1 × 107, 1 × 108and 1 × 109cells mL−1) on ‘Thompson Seedless’ grape berries at 20 °C. The strains m11, me99 and ca80 reduced the incidence ofB. cinereato 11.9, 26.1 and 32.1%, respectively, when the berries were submerged in a yeast suspension at a concentration of 1 × 109cells mL−124 h before inoculation withB. cinerea. The most favorable pH for antifungal activity was 4.6 in the three isolates. The three yeast strains secreted the hydrolytic enzymes chitinase and β-1-glucanase, and two strains (me99 and ca80) produced siderophores. The three yeast strains exhibited low oxidative stress tolerance and only strain m11 had the ability to produce biofilms. The strains were identified using 5.8S-ITS rDNA PCR-RFLP and correspond to theMeyerozyma guilliermondii(m11) andAureobasidium pullulans(me99 and ca80) species.