Cytokines are (glyco)proteins that are synthesized and secreted by various cells, which bind to specific receptors on target cells and which regulate activation, proliferation, and differentiation of immune as well as non-immune cells. Keratinocytes upon injury release interleukin (IL)-1, IL-6, IL-8, colony-stimulating factors, and tumor-necrosis factor, as well as growth and suppressor factors. There is also strong evidence for a network of interacting cytokines, which has been only partially characterized so far, maintaining a proper balance. However, excessive or insufficient production of these mediators may contribute to certain disease states, particularly those with infectious and autoimmune genesis. Therefore the understanding of cytokine interactions may be helpful in elucidating the pathomechanisms of such diseases. Moreover, certain cytokines, as well as their analogues and antagonists, may prove to be of therapeutic value.