Introduction: Psoriasis is a chronic inflammatory skin disorder determined by the activation of several immune cells and resident tissue cells. Various cytokines mediate inflammatory signals, including IL-23, which is an important factor involved in the differentiation of T helper (Th17) cells. Areas covered: Increasing evidence suggests that IL-23 is a central cytokine to the pathogenesis of psoriasis. An overview on both experimental and human data will be reported in order to support the hypothesis of a key pathogenic role of IL-23/Th17 axis. Expert opinion: Targeting IL-23 might be a more selective, valid and effective therapeutic approach, which, potentially, may show important advantages in terms of long-term efficacy and safety in the treatment of psoriasis. © 2014 Informa UK, Ltd.