Allergic diseases, particularly allergic asthma, are among the most frequent disorders seen in paediatric practice and clinic. Epidemiological data as well as recent immunological studies have largely contributed to the identification of risk factors eventually leading to the clinical manifestation of allergy. Various strategies of primary prevention are being developed and most of them include avoidance of identified or presumed risk factors. Another promising field of research investigates pharmacological approaches in the prevention of allergy, and drugs have been identified which interfere with the pathophysiological pathways. It seems likely that they may play an important role in future primary prevention strategies especially targeting infants at high risk.