Acute diarrhoea is a severe gruesome disease seen in children. WHO recommendation for the treatment of acute diarrhoea is limited to oral rehydration salts. But B. clausii has been used as an adjunct along with the ORT to reduce the duration of diarrhoea. Despite its popular use, there is a lack of data demonstrating the efficacy of B. clausii. This study is to systematically review randomized controlled trials that reported the efficacy and safety of B. clausii in the treatment of acute childhood diarrhoea.