Cytokines are small and membrane-bound protein-based cell signaling molecules that aid cell-to-cell communication in physiological and pathological processes. TNF-α is a pleiotropic cytokine, it is regarded as a principal cytokine in the acute and chronic phases of the immune and inflammatory response. TNF-α has been demonstrated to play a role in neuroplasticity and myelination, as well as excitotoxicity, neuroinflammation, and damage to the blood-brain barrier. The involvement of TNF-α in the etiology of Parkinson’s disease, both in its early and late stages, Alzheimer's disease, Multiple sclerosis, coronary artery disease has been substantiated using both experimental models and clinical studies. TNF also plays a key role in cardiovascular disease, initiating a cascade of inflammatory and vascular responses. The aim of this study is to clarify the molecular mechanisms of TNF action and the effects of its secretion in selected diseases.