Tumor necrosis factor alpha (TNF-alpha) is a protein of a cellular origin belonging to a group of proinflammatory cytokines. A rapid overproduction of TNF-alpha in a cerebral post-ischemic inflammatory response leads to the stimulation of adhesive molecules expression with subsequent accumulation of leukocytes in the ischemic focus, which is preceded by their adhesion and migration. The TNF-alpha proinflammatory activity results mainly in extending the area of the brain infarct, which brings about negative clinical implications. Being the final morphological effect of ischemic stroke, TNF-alpha appears also to contribute to neuronal necrosis by its involvement in the process of apoptosis as well as in the death of neurons. The present study describes and discusses mainly the contribution of TNF-alpha to the formation of ischemic focus in the brain.