In the absence of a reliable biomarker, instruments to measure AD disease severity are questionnaires, which are completed by patients, significant others or physicians. There is substantial heterogeneity in the way in which objective disease severity (i.e. clinical signs), subjective disease severity (i.e. symptoms) and quality of life are measured. The Harmonising Outcome Measures for Eczema (HOME) initiative has reached the consensus that the Eczema Area and Severity Index (EASI) for signs and the Patient-Oriented Eczema Measure (POEM) for symptoms are the preferred instruments to be measured in all clinical trials in AD. There is no well-validated way to measure AD disease severity by a global assessment. The Childhood Atopic Dermatitis Impact Scale (CADIS) is a promising proxy instrument to measure quality of life in infants and their family with one single instrument. Valid and feasible ways of measuring disease severity and quality of life in clinical practice are unclear; guidance should be sought from the recommendations for clinical trials for the time being.