This is a retrospective study based on the encoding and statistical analysis of data collected in patients followed within the Immuno-Allergology Service of the CHU Brugmann Hospital, who received an allergy assessment between 01/01/2015 and 31/12/2015. The allergens tested include: dermatophagoides pteronyssinus (DEPT), dermatophagoides farinae (DPF), blomia, cat, dog, cockroach, orchardgrass, timothy grass, alder, hazel,birch, olive tree, cypress, ash, latex, aspergillus, alternaria, cladosporium, peanut, hazel.