Previously we investigated the eczema prognosis and the risk of developing allergic asthma and rhinitis in a cohort of 94 children with atopic dermatitis. In this second study on the same cohort we address the development of sensitization to foods and airborne allergens, risk factors and, the question whether children with atopic dermatitis who will not become sensitized can be recognized early. Children with atopic dermatitis were followed up regularly from infancy or early childhood to 7 years of age with clinical examination and blood sampling. After age 3, skin prick tests with inhalation allergens were performed yearly. In most children both clinical allergy and sensitization to egg and milk were transient but those to peanut were persistent. Eighty per cent of the children became sensitized to airborne allergens and 75% of them noticed symptoms when exposed. Heredity for atopy and eczema, sensitization to hen's egg, and early onset of eczema entailed an increased risk of becoming sensitized. Children never sensitized had late onset of eczema and less heredity for atopic disease but did not differ in other respects from the sensitized children.