The German Environmental Survey for Children (GerES IV) is the environment-oriented module of the National Health Interview and Examination Survey for Children and Adolescents (KiGGS) which is being performed nationwide in Germany. From 2003 to 2006, a random subsample of 1800 children aged 3-14 years is being studied with regard to their body burden and health impairments linked to housing conditions and the personal environment- and health-relevant behaviour. The basic study programme includes the analysis of blood, urine, tap water and house dust as well as the application of an extensive questionnaire. The data gained from this population sample, which is representative for Germany's children, are the basis for deriving reference values to characterise the background exposure of children aged 3-14 years. Trends over time can be detected and the success of environmental policies verified by comparing the data with those of the German Environmental Survey 1990/92 (GerES II), also conducted in close cooperation with the National Health Survey, which included children aged 6-14 years. By linking the data from the Environmental and the Health Surveys, health-relevant environmental exposures can be detected and different scientific hypotheses can be tested. The main subjects that are being dealt with using subcollectives of GerES IV are 'VOC and eye and nasopharynx irritation', 'indoor allergens and allergic diseases of the respiratory system', 'chromium, nickel, fragrances and contact allergens', and 'noise, hearing capacity and stress hormones'.