Biotin production and the growth of the strains of Bifido-bacterium adolescentis, B. bifidum, B. breve, B, infantis, and B. longum were studied. These five strains showed heavy growth on BL medium. But when yeast extract medium (carbon source, glucose) was used, the extent of their growth was significantly decreased, one-half or less than that of the growth on BL medium. B. bifidum grew well on yeast extract medium containing oligosaccharides, such as isomaltooligosaccharide, and produced biotin extracellularly. The utilization of oligosaccharides in biotin production by these five strains was investigated.