Several yeast strains of the species Saccharomyces cerevisae, S. bayanus and S. paradoxus, first identified by hybridization experiments and measurements of DNA/DNA homology, were characterized using polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) analysis of the MET2 gene. There was no exception to the agreement between this method and classical genetic analyses for any of the strains examined, so PCR/RFLP of the MET2 gene is a reliable and fast technique for delimiting S. cerevisiae and S. bayanus. Enological strains classified as S. bayanus,S. chevalieri , and S. capensis gave S. cerevisiae restriction patterns, whereas most S. uvarum strains belong toS. bayanus . Enologists should no longer use the name of S. bayanus for S. cerevisiae Gal strains, and should consider S. bayanus as a distinct species.