Cytokines are small protein molecules, released by activated cells which function as chemical messengers between cells of the immune, inflammatory and other systems. After more cytokines were identified, and in order to avoid confusion, immunologists started naming some of the cytokines 'interleukins' and numbering them as they were found. Interleukins are involved in processes of cell activation, cell differentiation, proliferation, and cell-to-cell interactions. The same interleukins can be produced by many different cell types and an individual interleukin may act on different cell types, eliciting different biological responses, depending on the particular type of cell. They are synthesized after cell activation as a consequence of a physiological or non-physiological stimulus. Some interleukins are autoregulatory and regulate their own synthesis or the expression of their own receptors.The experimental evidence implicates interleukins in the pathogenesis of different rheumatic and autoimmune diseases. Interleukins are commonest causes of joint failure as interleukins are involved in the degeneration of connective tissue in cartilage and bone. The various cytokines levels in blood and other body fluids seems to be useful to monitor disease activity or monitor treatment or evaluate the need for treatment. An excellent marker of flaring in inflammatory conditions is IL-6, being raised 24 hours before C-reactive protein. Levels of IL-1, TNF, IL-8 and TGF-β in tissues and of IL-2 and TNF-α receptors in the joint fluids and blood, have also been shown to correlate with disease activity. IL-1 can exert a variety of systemic effects, including induction of local joint effects mediating production of fibroblast fibronectin and tissue collagenase. IL-6 is found in greater quantities in the synovial fluids from patients with rheumatoid arthritis compared to osteoarthritis. Synovial fluid IL-6 levels correlate with local IgM rheumatoid factor and systemic acute phase protein production. Chemokines, including IL-8, have potent chemotactic activity for cells of the immune system. IL-8 not only participates in the inflammatory phase of rheumatoid arthritis, but also participates in the vasculoproliferative phase of this disease. Recent data on the cytokine profile in inflammatory rheumatic diseases implies that alternative treatment strategies should be considered. Potential approaches for modifying the cytokine network include inhibition of cytokine production or their action, inhibition of signal transduction and administration of suppressive cytokines.