Soluble cytokine receptors are more general phenomena and play a wider physiological role in the regulation of the immune system than previously recognized. Soluble TNF receptors - sTNF-Rp55 and sTNF-Rp75 by ability to bind to free TNF-a might play a regulatory role in a variety of normal and abnormal reactions mediated by TNF-a. Increase of sTNF-Rs levels have been observed in the serum of patients with a different diseases. Measurement of soluble TNF receptors concentrations seems to be a significant indicator in prognostic estimation of some diseases. Additionally, bioengineered soluble receptors may prove useful as specific cytokine-inhibiting therapeutic agents.