Cytokines are proteins that regulate immune and inflammatory reactions as well as haematopoiesis. This group of molecules is very heterogeneous including, for example, several interleukins (IL), tumour necrosis factors (TNF) and colony-stimulating factors (CSF). The cytokines participating in the regulation of the inflammatory response are IL-1, IL-1 receptor antagonist (IL-1RA), IL-6, IL-10 and TNF. Functionally they can be divided into proinflammatory (IL-1, IL-6, TNF) and anti-inflammatory (IL-1RA, IL-10) molecules. There is evidence that the inflammatory response must be finely tuned: too strong a response causes the various adverse effects associated with infectious and autoimmune diseases, while a weak inflammatory response attenuates the subsequent immune response. It has now been demonstrated that several of the cytokine genes are polymorphic. In this review we describe the polymorphisms of the two inflammatory cytokines, IL-1 and IL-10, and their significance in various diseases of autoimmune or inflammatory nature.