A new sugar substitute, Palatinit®, is an equimolar mixture of the disaccharide alcohols α-D-glucopyranosyl-1,6 sorbitol and α-D-glucopyranosyl-1,6 mannitol. Palatinit can be produced on an industrial scale from sucrose. Representative isolates of the predominant oral genera of streptococcus and actinomyces were tested for their ability to ferment Palatinit in vitro. Some strains of Streptococcus mutans, Actinomyces israelii, Actinomyces viscosus and Actinomyces naeslundii lowered the pH to below 5.5. These data, however, give no information on the rate of acid production from Palatinit or the pH drop in dental plaque in vivo. Palatinit-fermenting microorganisms were found in dental plaque of rats. Following administration of Palatinit to rats, no increase in the numbers of these microorganisms was observ