Valid questions for atopic eczema are necessary to identify risk factors in epidemiological studies. We have examined the influence of cultural and educational factors on the validity of some questions on atopic eczema used in the International Study of Asthma and Allergies in Childhood by using data from a cross-sectional study on 1511 children aged 6 years from East and West Germany. We tested three questions in relation to a point prevalence of atopic eczema as recorded by a dermatologist: (i) has a physician ever diagnosed eczema in your child? (ii) Has your child ever had an itchy rash which came and went for at least 6 months? (iii) Has your child ever had 'neurodermatitis' (atopic eczema, endogenous eczema)? The point prevalence of atopic eczema on the day of investigation was 11.1% (134 of 1217). According to the questionnaire, 15.7% of the children had had physician-diagnosed eczema, 14.1% had had neurodermatitis and 11.3% had had an itchy rash for > 6 months. Fifty-one per cent of parents who had a child with atopic eczema on the day of investigation said that their child had had an itchy rash which came and went for at least 6 months. This sensitivity value is less than that found in another community survey conducted in the U.K., suggesting that the German wording of the question seems to mean something more severe to the parents than the English one. The education of the parents had an influence on the validity of the three questions: parents with < 10 years of schooling often answered symptom and diagnosis questions less positively. Parents with academic degrees, contrary to expectation, did not answer most precisely, this being especially true for the symptom questions. The association between symptom questions and clinical diagnosis was higher in West than in East Germany. We compared lifetime eczema symptoms and diagnosis with a point prevalence clinical diagnosis. In the absence of knowledge of how extraneous factors measured in this paper can affect diseases chronicity, it is difficult to say with certainty that such factors affect the validity of symptom and diagnosis questions on atopic eczema. Our study suggests that more studies are needed to examine the influence of social class, education and location on the validity of symptom questionnaires for atopic eczema. Until then, we recommend that information about such variables should be gathered routinely.