The prevalence of atopic dermatitis (AD) in children has considerably increased in industrialised countries over the past 20-30 years. Determination of the interest of supplementary examinations, notably allergological explorations, is fundamental for all the practitioners who manage children suffering from the disease. ALLERGOLOGICAL TESTS: WHEN AND FOR WHO? Children suffering from eczema and describing concomitant manifestations such as urticaria, an oral syndrome or asthma should benefit from allergological tests. The latter are conducted as markers of the progression in the infant (aged under 24 months) presenting with atopic eczema without any concomitant manifestations. Such tests are aimed at defining the prognosis of AD and specifying the risk of progression towards an asthmatic syndrome. Allergological tests are conducted in the case of severe AD of early onset and in the presence of a family history of atopy. ALLERGOLOGICAL TESTS: WHICH? They explore immediate and delayed hypersensitivity. They include determination of IgE-dependent sensitivity using cutaneous tests or specific IgE measurements with validated methods. Allergy to food concerns very young children of around 2 years old. The diagnosis of such allergies is based on the efficacy of the eviction and oral provocation test, when there is discordance between the clinical history and the results of the determination of a specific IgE-related sensitivity. Prick-tests are performed to search for contact hypersensitivity, more frequent in older children. They are performed for contact allergens, aero-allergens and foodstuff and are supplemented by interrogation data. The pertinence of such tests remains to be determined. ALLERGOLOGICAL TESTS: WHAT FOR? An allergic factor enhances AD in one child out of two. Evictions adapted to the results of the allergological tests always improve the status of the children. They may even modify the natural history of the disease.