Reduced glutathione (GSH) is the main intracellular non-protein thiol compound. GSH is important in a variety of reactions including reductive processes, protection of cells against oxidative stress, free oxygen species and other toxic compounds of endogenous and exogenous origin. In the cardiovascular field, thiol compounds may protect against ischaemia-reperfusion injuries, regulate enzyme activities and modify the function of organic nitrates and vascular tone. Metabolic manipulation with thiol compounds (i.e. by treatment with N-acetylcysteine or oxothiazolidine) may provide a safe method for protecting cells against ischaemia and may be a relevant supplement to current cardiovascular therapy.