We obtained anti-allergic oligosaccharides from a sweet potato-shochu distillery by-product (SDB).Oral administration of oligosaccharides A and B in SDB to ovalbumin/aluminum-sensitized mice for 4 weeks resulted in a significant decrease in serum IgE concentration. The release of β-hexosaminidase from rat basophilic leukemia cell line RBL-2H3 was also suppressed by the addition of oligosaccharides A and B to the cell culture. The molecular weights of oligosaccharides A and B were about 730 and 530, respectively, determined from the retention time on Bio-Gel P-2. Oligosaccharide A was composed of galactose, glucose and uronic acid in a molar ratio of 2:1:1. Oligosaccharide B was composed of galactose, glucose and arabinose (1:1:1 molar ratio) or galactose, glucose and uronic acid (1:1:1 molar ratio), showing that oligosaccharide B is a heterogeneous mixture of other oligosaccharides. Oligosaccharides A and B exhibited growth-stimulating activity with Bifidobacterium lactis BB-12. The present results indicate that the oligosaccharides in SDB are promising ingredients for the effective control of allergic diseases via suppression of IgE production and inhibition of basophilic leukemia cells degranulation.Keywords: anti-allergy, shochu by-product, oligosaccharide, suppression of IgE production, suppression of β-hexosaminidase release, Bifidobacterium growth stimulation *To whom correspondence should be addressed. E-mail: t.yonemoto@satsuma.co.jp IntroductionShochu is a traditional alcohol spirit in the south of Japan. After alcoholic fermentation of sweet potato with rice Koji and yeast, the alcohol and other volatile components were distilled. Sweet potato-shochu distillery by-product (SDB) contains numerous components originating from its raw materials, rice malt and yeast, and is rich in nutrients, including oligosaccharides, peptides, dietary fiber, polyphenols and vitamins. There are many reports on the functions of SDB,