Genetic disposition, exposure to allergens and additional factors that favour the manifestation, are the relevant conditions for IgE-mediated atopic allergies. Among a group of markers of atopy, only family history and cord-blood-IgE are of practical relevance as predictors of the disease. No parameter identifies all children at risk, but cord-blood-IgE seems the best in predicting severe diseases. Recent studies demonstrate possibilities and limitations of programs in atopy prevention. The effects are antigen-specific and limited to the time of elimination. Some food allergies form exceptions to this rule, because their manifestation is limited to a vulnerable period and can thus be prevented completely by elimination. The present state of knowledge shows hydrolysed milk preparations to be useful for the prevention of cow's milk allergies.