Excess of free radicals, bearing unpaired electrons takes part in cell damage mechanisms, premature aging and cell death. Appropriate antioxidative potential is maintained due to the presence of antioxidative enzymes, endo- and exogenous compounds, which inactivate reactive oxygen species. An essential element of this system is lipoic acid which serves not only as a coenzyme of citric acid cycle enzymes, but at the same time demonstrates antioxidative activity as well as takes part in endogenous antioxidants regeneration (e.g. glutathione, coenzyme Q10). Its therapeutic application concerns mainly prevention and treatment of diabetic polyneuropathy, however latest data suggests its potential application also in a number of conditions in which free radical mechanisms are involved.