Chitin was present as a main component occupying about 15% of the cell wall preparation of Zygosaccharomyces rouxii ATCC 52698 grown in a non-salt medium, and a netlike structure spreading on the whole cell surface, that mainly consisted of chitin, was observed by an electron microscope after treating the cells with an excess of Zymolyase. The amounts of chitin, however, remarkably decreased according to the increase in NaCl in the medium. The net like structure was not observed entirely on the cell envelope of the yeast grown in a hypertonic salt medium, and the ratio of chitin contained in the cell walls decreased to 1-2%.