Atopic dermatitis (AD) and psoriasis vulgaris (Pso) represent the most frequent chronic inflammatory skin diseases. It has been assumed for a long time that these diseases have a completely different background. Recent findings about the genetic, epidemiologic and pathophysiologic factors of both diseases have remarkably improved our knowledge about the complex mechanisms underlying AD and Pso. Beyond that, in view of these findings, the question arises, which similarities and differences between AD and Pso exist. In order to address this point, we provide an overview about the current knowledge in the field of AD and Pso.