While fermentation of 20 g glucose l(-1) by Saccharomyces cerevisiae was not impaired by high NaCl concentrations, fermentation of 20 g maltose l(-1) was significantly decreased by 0.7 M NaCl, and completely inhibited with 1.4 M NaCl. No glycerol was produced in response to the salt stress when yeast cells were fermenting maltose. Active maltose transport, and not intracellular hydrolysis, was the metabolic step severely impaired by the NaCl stress.