In the present work, the influence of Cu concentration on alcoholic fermentation by Saccharomyces cerevisiae was studied in white grape musts and in YNB medium containing glucose. In the YNB medium, the yield of ethanol, relative to the control, doubled in the presence of 0.50 and 1.0 mM Cu. As for production of ethanol from musts, only minor effects were observed at different Cu concentrations, which indicates that Cu levels do not effect changes in fermentation, and, therefore, are below any toxic level regarding the yeast performance.