Muscle tissue is unique in its requirement and ability to undertake very rapid and co-ordinated changes in energy supply and oxygen flux during contraction. Several studies have suggested that this renders the tissue particularly prone to oxygen radical-mediated damage. Free radicals have been postulated to play a role in muscle damage induced by different forms of exercise and in various pathological disorders, such as the muscular dystrophies, malignant hyperthermia and alcoholic myopathy. However, conclusive evidence for a fundamental role for free radicals and protective effect of antioxidants remains elusive in all these situations and much further work on the relevant pathogenetic mechanisms is still required.