Abstract: Probiotics have been defined as living microorganisms, which upon ingestion in certain numbers have beneficial effects on human health beyond inherent general nutrition. These effects are attributed to the restoration of increased intestinal permeability and unbalanced gut microflora, improvement of the intestine`s immunological barrier functions and alleviation of the intestinal inflammatory response. The application of probiotics in pediatric practice currently lies in enhancing these barrier functions in the gut and reducing the risk of diseases associated with their dysfunction. It has been widely accepted that human milk is the best food for infants. Although human milk is the first choice for the newborn infant, milk substitutes play an indispensable role in infant nutrition when breast-feeding is not possible, desirable and sufficient. Infant milk formulas have been designed to provide infants with the required nutrients for optimal growth and development. In this concept probiotic bacteria (such as lactobacilli and bifidobacteria) have been successfully used in infant formulas. Several studies have been carried out using probiotic bacteria in the treatment or prevention of infectious diarrhea and allergic diseases. It has been also demonstrated that supplementing with Bifidobacterium animalis BB-12 or Lactobacillus GG modifies the allergic inflammation in infants with atopic eczema. Furthermore a number of fermented dairy products have already been developed by using specially selected strains of lactobacillus and bifidobacteria for infant feeding. Although most of these products have been used safely for years, results of scientific researches should be evaluated carefully before routinely recommending these products, especially for children.