The prevalence of asthma has been studied in Tokelauan children aged 0--14 years in two environments--Tokelau and New Zealand. Only 11.0% of the 706 children examined in Tokelau were classified as asthmatic, whereas 25.3% of the 1,160 children seen in New Zealand were asthmatic. For those children examined in New Zealand there was no significant difference in the prevalence of asthma between those children who were born in New Zealand and those who were born in Tolelau.