The fermentation of grape juice into wine is a complex microbiological process, in which yeasts play a central role. Traditionally, identification and characterization of yeast species have been based on morphological and physiological characteristics. However, the application of molecular biology techniques represents an alternative to the traditional methods of yeast identification and are becoming an important tool in solving industrial problems. Although Saccharomyces cerevisiae is responsible for the alcoholic fermentation, the presence of non-Saccharomyces species could be important since they produce secondary metabolites, which can contribute to the final taste and flavor of wines.