The dietary habits of 73 children seen consecutively in a dermatology out-patient department were studied to ascertain the nature and frequency of dietary manipulation and to assess any potential hazards. Although most children had only mild flexural dermatitis, 71% had had significant alterations made to their diet before attendance at hospital. Almost all diets were unsupervised and only six children had seen a dietitian. Over half had been started on diets before any professional advice had been sought. Information on diet had come from media, books or magazines (51%), friends (32%), general practitioners (27%) and district nurses or health visitors (18%). The major dietary alterations included the exclusion of eggs, dairy products and food additives, and the use of soya and goat's milk. Under 10% of patients claimed benefit from these largely unsupervised diets. Harmful practices included the frequent use of unboiled, unpasteurized goat's milk, unmodified goat's milk in a baby of 4 months and the use of severely restricted diets. Three children (6%) in the diet group had been on diets which were considered by a hospital dietitian to be particularly dangerous. However, there was no evidence of growth retardation, failure to thrive or specific deficiency syndromes in the group we studied. Uncontrolled, unsupervised and often prolonged dietary alterations are commonplace in children with atopic dermatitis. This is a potentially serious health problem.