This study evaluated the effects of processing grape with different proportions of mealybug-infested bunches in wine quality in cultivars Chardonnay and Carmenere. No differences in chemical composition of musts were found. Basic chemical composition for white and red wines was similar. In both cultivars total polyphenols decreased as the proportion of infested bunches increased, from 266 to 239 (mg L-1 gallic acid) in Chardonnay and 2124 to 1820 in Carmenere. The same trend was observed in Carmenere for anthocyanins and tannins, by spectrophotometry and high performance liquid chromatography. Dimethyl amino cinnamaldehyde index in Carmenere went from 28.6 in wines 100% healthy bunches to 22.0 for the 100% infested, and tannin galoilation went from 3.85 to 0.74%. Sensory analysis showed that wines with larger proportion of infested grapes were associated with negative descriptors and lower quality. These results show that mealybugs have the potential of negatively impacting wine quality and this deserves further attention.