Bifidobacterium bifidum has been used in foreign to treat antibiotics induced diarrhoea with many advantages compared to Bacillus subtilis. But in Vietnam, there are not like this. We have researched a basis to use this bacterium in a pharmaceutical product. We isolated, screened the optimal conditions to culture B. bifidum and built up the growth curve of it. An in vitro trial had been developed on rat and showed that B. bifidum had a good effect on treatment antibiotics induced diarrhoea.