By genetic hybridization, molecular karyotyping and Southern hybridization with the ADC1 promoter probe three species Saccharomyces cerevisiae, S. paradoxus and S. bayanus were identified among wild Saccharomyces sensu stricto yeast in Spain. Wine strains fermenting melibiose belong to the biological species S. bayanus (syn. S. uvarum). S. kluyveri has been detected karyotypically.