Two hundred and thirty-four yeasts belonging to 14 generawere assayed for bio-fungicidal activity. All strains had been iso-lated from different viticultural environments. Nineteen strainswere isolated from Redglobe table grapes (Zonda, San Juan), 8 fromvineyard soil (Caucete, San Juan) and 207 from fermenting mustsof different grape varieties from San Juan, Argentina. None of theyeasts increased the level of berry rot. Identification of the strainsyielded 140 Saccharomyces and 94 non-Saccharomyces