**Abstract**

Wine is a complex matrix that involves compounds of different chemical nature, with volatile compounds being primarily responsible for the aromatic quality of the wine. The formation of these volatile compounds is mainly due to yeasts' metabolism during alcoholic fermentation. Several studies in the microbiology field have reported that *Saccharomyces cerevisiae* is responsible for alcoholic fermentation, influencing the sensory quality of the wine and affecting the metabolic activity of other genera and species of yeasts, called non-*Saccharomyces*, which would positively affect sensory quality. Non-*Saccharomyces* yeasts, considered until recently as undesirable or spoilage yeasts, can improve the chemical composition and aroma profile of the wine. The activity of these yeasts is considered essential for the final wine aroma profile. Thus, the metabolism of these microorganisms could be a decisive factor that strongly influences the aroma of the wine, impacting on its quality. However, there are few studies that explain the impact of non-*Saccharomyces* yeasts on the final wine aroma profile. This chapter summarizes relevant aspects and pathways involved in the synthesis of aromatic compounds by non-*Saccharomyces* yeasts as well as studies at the genetic and transcriptional level associated with their formation.

**Keywords:** wine, non-*Saccharomyces* yeasts, fermentation, aroma, flavor
