For prevention of antibiotic-associated diarrhoea (AAD), Bacillus clausii (B. clausii) strains O/C, SIN, N/R and T are commonly used. B. clausii demonstrated a lower incidence of diarrhoea with antibiotics in adults in a controlled trial when compared to placebo. Less is known about the same in the case of children. This study combines the data of 3 trials and shows a significant difference in the efficacy of B. clausii in preventing AAD in children.