Tumor necrosis factor-α (TNF-α) is a pleiotropic cytokine which, as a part of complex cytokine system, controls the synthesis and expression of other cytokines and their receptors through the activation of cytokine cascades. The aim of our study was to test the effects of TNF-α on the secretion of interleukin-6 (IL-6) from cultured human muscle. We studied these effects before and after the fusion of myoblasts into multinucleated myotubes. Cultures, prepared from satellite cells isolated from the muscle pieces routinely discarded at some orthopaedic operations were treated with TNF-α at three different concentrations. We found that TNF-α increases the IL-6 secretion in a concentration dependent manner. Quantitatively, secretion from myotubes exceeded the secretion from myoblasts indicating that secretion is differen­tiation stage-dependent. The presence of TNF-α receptor was confirmed by Western blot. Apoptosis, followed by DNA fragmentation, remained unchanged. Our results support the concept that skeletal muscles actively participate in cytokine signalling in critical clinical con­ditions.