In this paper we describe the development and validation of a questionnaire for atopic dermatitis used in population surveys in Denmark. The Danish questionnaire was developed from the UK Working Party's questionnaire for atopic dermatitis and includes a severity score. The study included 61 children aged 3 to 14 years recruited from our Department of Dermatology, two kindergartens and a primary school. A validator was appointed to evaluate whether each child had current or previous atopic dermatitis. Compared to the validator's diagnosis, the sensitivity of the UK Working Party criteria was 90% (95% CI; 74-98) and the specificity was 97% (95% CI; 82-99). The criteria for atopic dermatitis have a satisfactory sensitivity and specificity for diagnosing current atopic dermatitis, but the natural course of the disease complicates the validation of investigational instruments. We suggest that future epidemiological studies aimed at establishing new knowledge on atopic dermatitis should include history, current symptoms and findings and a severity score.