Atopic dermatitis (AD) is a strongly heritable, chronic relapsing dermatosis that frequently co-occurs with other atopic phenotypes including asthma and allergic rhinitis (the so-called atopic triad disorders). However, despite high levels of co-morbidity, relatively low levels of genomic co-incidence have been observed between atopic triad disorders. Conversely, current mapping data have revealed a striking pattern of co-localisation between AD disease loci and those mapped using another chronic dermatological disease – psoriasis. In this review, we examine the evidence for co-localisation between AD and a range of atopic, infectious, inflammatory and autoimmune diseases, and consider the implications of these data for the AD disease concept and future research in the field.