Abstract: L. casei DN 114-001 is a bacterial agent known for its utility in the fermentation of milk products. A fermented milk product comprising as the sole bacterial agent L. casei DN 114-001 is effective in reducing the number of rotavirus associated diarrhea episodes experienced by infants up to 24 months of age. In particular, the number of rotavirus associated diarrhea episodes, as well as their severity and duration is reduced in children receiving milk products fermented with L. casei DN 114-001, present in the fermented milk product in amounts of at least 106 CFU/g. L. casei may be the sole bacterial agent present in the fermented milk product, and yet effective reduction of diarrhea episodes associated with rotavirus infection is obtained.