The International Study of Asthma and Allergies in Childhood <sources.htm#surveys> included 463,801 children aged 13-14 years from 155 centres in 56 countries worldwide. The results for prevalence in the past year are shown here. Substantial variation is evident both within tend between countries. The lowest prevalences were found in parts of Eastern Europe and central Asia, with high prevalences reported from centred in several regions of the world, including Britain.