As the growth factor of lactic acid bacteria, LD (trehalose) was isolated fromLentinus edodes by using silica gel column chromatography. LD induced the growth ofBifidobacteria breve andLactobacillus brevis, which were isolated from human feces. LD selectively induced the growth of lactic acid bacteria among total microflora. When total intestinal microflora were cultured in the medium containing LD, it stimulated the growth of lactic acid bacteria and inhibited harmful enzymes, beta-glucosidase, beta-glucuronidase, and tryptophanase, of intestinal bacteria. LM, which was a monosaccharide fromL. edodes, induced the growth of lactic acid bacteria but it seems to be invaluablein vivo. LH isolated fromL. edodes by Sephadex G-100 column chromatography was not effective for the growth of lactic acid bacteria.