Infant and follow-on (or "follow-up") formulae fermented with lactic acid-producing bacteria during the production process contain no viable bacteria in the final product due to their inactivation by heat or other means. In this article the ESPGHAN Committee on Nutrition reviews published information on their clinical evaluation. In a systematic literature review, 2 randomized clinical trials including 933 infants were identified as meeting our predefined inclusion criteria. Our analysis reveals that only limited published data are available on the effects of fermented infant formulae. There are indications from 2 studies that some fermented infant formulae may reduce the occurrence or severity of infectious diarrhea in infants. It is recommended that the effects of fermented infant formulae on infectious diarrhea and other relevant outcomes should be assessed in further randomized controlled trials according to current scientific standards. The available data do not allow general conclusions to be drawn on the use and effects of fermented formulae for infants.