Probiotics are defined as 'live micro-organisms that confer a health benefit on the host if administered in adequate amounts'. There are only limited data in the literature regarding the efficacy and safety of lactobacilli for various gastrointestinal indications in children. Lactobacillus rhamnosus GG (LGG) has no added value in the treatment of children with functional constipation. Lactobacilli do seem to be effective in rotavirus diarrhoea. They seem safe and shorten the duration of the diarrhoea by about 1 day. For the prevention of infectious diarrhoea, lactobacilli are only moderately effective and the clinical relevance is unclear. There is 1 controlled study in which LGG had a preventive effect on the development of atopic eczema (but not of allergy to cow's milk) in newborn infants.