It is unclear whether eczema prevalence is truly increasing worldwide.We sought to investigate worldwide secular trends in childhood eczema.Children (n = 302,159) aged 13 to 14 years in 105 centers from 55 countries and children aged 6 to 7 years (n = 187,943) in 64 centers from 35 countries were surveyed from the same study centers taking part in Phase One and Three of the International Study of Asthma and Allergies in Childhood by using identical validated and translated questionnaires. The results indicate that the epidemic of eczema seems to be leveling or decreasing in some countries with previously high prevalence rates. The picture elsewhere is mixed, with many formerly low-prevalence developing countries experiencing substantial increases, especially in the younger age group. JACI. 2008;121(4):947-54.