Respiratory symptoms, bronchial hyperresponsiveness (BHR) and atopic status were measured in 1,217 schoolchildren, aged 8 to 12 years, living in the Villawood area of the city of Sydney. The findings are compared to those from studies previously conducted, using identical protocols, in the inland town of Wagga Wagga and in the coastal town in Belmont, NSW. There was a higher prevalence of respiratory symptoms in Villawood and Wagga Wagga (40%) than in Belmont (29%). The prevalence of BHR was 15% in Villawood and Belmont and 20% in Wagga Wagga. However, the distribution of severity of BHR was similar in each study town, reflecting the same pattern of responsiveness. The percentage of children who were atopic was higher in Villawood (44%) than in inland Wagga Wagga (39%) or coastal Belmont (40%). Children in the three areas differed in their reactions to the predominant allergen groups. There were more children who were reactive to grass pollens in the inland area and more children who were reactive to house dust mites in the coastal area. Children in Villawood had a high prevalence of reactivity both to house dust mites and to grass pollens. The Villawood children who were born in Australia had a higher prevalence of respiratory symptoms, of BHR and of atopy than the foreign-born children.