Objective To study the subchronic toxicity of Bifidobacterium animalis V9,and to determine its no-observable-adverse-effect-level(NOAEL).Methods Eighty Sprague-Dawley rats were randomly divided into four groups,twenty rats(10 males and 10 females) per group.Animals in the three treatment groups were given 1.25,2.50,and 5.00 g/kg BW of test material by gavage for 90 days respectively,and rats in the control group were treated with the same volume of water by gavage for 90 days.Clinical observations were conducted daily.Body weights and food consumption were recorded weekly.Blood samples were collected from all rats on the Day 46 and at the termination of the study,and gross examinations were performed on all animals euthanized for necropsy.Organ weights were recorded and selected tissues were examined microscopically.Results All parameters including body weight,food consumption,clinical biochemistry,absolute and relative organ weights and histopathology in treatment groups had comparable values to animals in the control group.Differences on hematology between treated and control groups were not treatment-related.Conclusion The NOAEL of B.animalis V9 were 5.00 g/kg BW in male and female rats,which was the highest dosage tested in this study,was equivalent to 300 times of the dosage recommended for human use.