Atopic dermatitis beginning in adult life is not mentioned in the medical literature. In a review of 2604 patients attending a contact dermatitis clinic, 243 patients (9%) were diagnosed with atopic dermatitis which began for the first time at 20 years of age or older with no contact factors present. This compares with 213 patients (8%) who had atopic dermatitis and contact dermatitis. Patients with purely atopic dermatitis had negative patch testing to relevant allergens and the diagnosis was based on a personal or family history of atopy as well as elevated IgE levels and multiple positive skin prick tests. A broad range of age of onset was found, as well as a female preponderance. The commonest sites of dermatitis were generalized involvement, dermatitis of the hands or eczema involving the face.