Exposure of atopic dermatitis (AD) patients to aeroallergens or food allergens can exacerbate or maintain the disease. Atopy patch tests (APTs) are able to identify these triggering factors and consist of the epicutaneous application of allergens for 48hours with evaluation of the resulting eczematous lesions after 48 and 72hours, according to the reading criteria of the European Task Force on Atopic Dermatitis (ETFAD). APTs show a higher specificity than skin prick and specific IgE tests, since the pathophysiological mechanism of the reaction induced is very similar to what occurs in AD lesions. The standardization of APTs to aeroallergens has brought a certain degree of reliability to this method, which is not the case for food APTs, where the positive predictive value must be improved in order to avoid any unnecessary dietary restrictions. Thus, optimization of APTs and furtherance of knowledge of the pathophysiology of eczemas could help to develop new immunobiological diagnostic methods and AD-specific immunotherapy.