Summary Background  Atopic dermatitis (AD) has a wide spectrum of dermatological manifestations and despite various validated sets of diagnostic criteria that have been developed over the past decades, there is disagreement about its definition. Nevertheless, clinical studies require valid diagnostic criteria for reliable and reproducible results. Objective  To summarize the evidence concerning the validity of diagnostic criteria for AD. Methods  All data sources were identified through searches on Medline, Embase and Cochrane databases. The Quality Assessment of Diagnostic Accuracy tool (QUADAS) was used. Results are presented in a receiver operating characteristic (ROC) plot. Results  Out of the 20 articles that met the criteria, 27 validation studies were identified. In two studies concerning Hanifin and Rajka diagnostic criteria sensitivity and specificity ranged from 87·9% to 96·0% and from 77·6% to 93·8%, respectively. Nineteen validation studies of the U.K. diagnostic criteria showed sensitivity and specificity ranging from 10% to 100% and 89·3% to 99·1%, respectively. Three validation studies concerning the Schultz‐Larsen criteria showed sensitivity from 88% to 94·4% and specificity from 77·6% to 95·9%. In one article concerning the criteria of Diepgen, the sensitivity ranged from 83·0% to 87·7% and the specificity from 83·9% to 87·0%. One article studied the Kang and Tian criteria and reported 95·5% sensitivity and 100% specificity. One article validating the International Study of Asthma and Allergies in Childhood (ISAAC) criteria showed a positive and negative predictive value of 48·8% and 91·1%, respectively. Conclusion  With this systematic review of the existing sets of diagnostic criteria for AD a varying number of validation studies with varying methodological quality was found. The U.K. diagnostic criteria are the most extensively validated. However, improvement of methodological design for validation studies and uniformity in well‐validated and applicable diagnostic criteria are needed to improve future intervention studies and to compare study results.