Acute oral toxicity of Bifidobacterium breve K-110, Bifidobacterium breve K-111, Bifidobacterium infantis K-525 were studied in Sprague-Dawley rats of both sexes. In this study, we examined number of deaths, clinical signs, bod weight and gross findings for 14 day after single oral administration of B. breve K-110,B. breve K-111 or B. infantis K-525 with different levels. They did not show any toxic effect in rats and oral LD$_{50}$ value was over 5 g/kg in rats.s.