Probiotics administration has been claimed to prevent antibiotic-associated diarrhea. The investigators thus conducted a double blind, placebo controlled study of providing probiotics to infants and children with severe bacterial infections and receiving broad spechum antibiotics. The results of the study showed that the group receiving probiotics had fewer diarrheal episodes (37.5%) than the control group (80%), although the numbers were too small for statistical analysis. In conclusion, probiotics administration to patients receiving high doses of broad spectrum antibiotics may prevent the occurrence of antibiotic-associated diarrhea. A further study with a larger number is required.