This study was carried out to evaluate the influence of the lipase-producing yeasts, present in the brine, on the quality of table olive oil. The oily fraction of olives processed microbiologically using the Beta-glucosidase-positive, lipase-negative yeast Candida wickerhamii 1542 showed an excellent quality, such as the typical extra-virgin olive oil. In contrast, the quality of the oily fraction of olives debittered microbiologically with the Beta-glucosidase- and lipase-producing yeast Williopsis californica 1639 worsened dramatically to such a point that the acidity of the oily fraction increased more than 90%. The microbiological analysis of brines showed that the lipase-producing yeasts are part of the natural yeast population of the brine, and when their presence is high, it can damage significantly the quality of table olives. The lipase-producing yeast W. californica 1639 in the brine showed the maximum lipolytic activity at pH 6, while the NaCl of the brine, at the maximum concentration of 12%, inhibited lipase activity by 70%. The concentration of the polyphenols present in the brine was not able to control the lipolytic activity of W. californica 1639 during the microbiological debittering process of table olives.