We are still at an early stage in the development ofconsistently effective probiotics for human application.Although the market for probiotic containing productsshows a substantial increase in popularity recently,scientific approaches to establishing the functionalbenefits of probiotic foods are still a complicated case.Evidence from in vitro studies suggests beneficial effects,but considerable progress has not yet been made in botheffects on host health and mechanisms of action. Also,whether specifically viable microorganisms are necessaryfor health benefits, needs clarification.The typical poor growth of these probiotic species ishighlighted, therefore investigation of bifidogenic- andgrowth factors, and efforts to establish optimumenvironmental conditions for their growth are critical,in addition to effects of the type of foods and storageconditions on microbial survival Criteria for the selection of effective microbial strainsfor a probiotic affect have to be established. New speciesand more specific strains of probiotic bacteria areconstantly being identified. Genetic modifications arecontinuously applied to improve fermentation efficiencyand shelf life of probiotic bacteria. However, the safetyof these modified bacteria should be considered.Incorporation of AB-cultures into other food commodities such as cheese is promising and should beintensively investigated