GSSG via the pentose phosphate pa.thway is inadequate, the ability to synthesize glutathione impaired, or the sulphydryl stability of haemoglobin decreased; (e) GSH assumes a vital role when either normal or abnormal erythrocytes are exposed to aromatic catalysts, by helping to absorb the vastly increased oxidative potential, and thus with the aid of the process of methaemoglobin formation to buffer against irreversible damage.It is recognized that this unified concept may fail to account for possible contributory factors. The ideas are put forward in order to direct attention to the selectivity of different forms of oxidant haemolysin, and to emphasize the variable significance of the protective role of GSH in different types of human erythrocyte placed under varying degrees and types of oxidative stress.