New molecular methods of research have greatly expanded the knowledge about the role of cytokines in several diseases, including psoriasis. The work orchestrated by these peptides is essential for the communication between resident inflammatory cells (keratinocytes and endothelial cells) and infiltrating cells (neutrophils, lymphocytes, Langerhans cells). This is a complex network due to redundancy, synergism and, sometimes, the antagonism of cytokines, which prevents full understanding of the pathogenesis of the disease. Currently, it seems premature to try to establish a main actor, but TNFalpha participates in all stages of psoriatic plaque development, as we shall see.