For survival, living cells maintain their thiol redox status within acceptable limits by three different mechanisms: i. glutathione disulfide export, ii. reduction of glutathione disulfide by pentose phosphate pathway and, iii. reduction of glutathione disulfide by Protein-SH. To assess the relative contribution of each one of the systems, intracellular [glutathione], [glutathione disulfide] and their export, in fresh and aged erythrocytes subjected to oxidative stress, in +/-glucose and +/-antioxidants, were measured. Glutathione was rapidly oxidized by tert-butylhydroperoxide in +/-glucose in both groups. The regeneration of glutathione, in both groups, in +/-glucose was about 100 and 50%, respectively. In parallel, intracellular glutathione disulfide concentrations were increased by about 200-350%. The protective effects of ascorbate and alpha-tocopherol were similar and they behaved like radical scavengers. In the absence of glucose, glutathione regeneration depends solely on the reduction of glutathione disulfide by protein-SH, and so it remained at about 50%. In the presence of glucose, the pentose phophate pathway was also involved and the regeneration approached 100%. Since glutathione or glutathione export correspond from 0 to 1% of total cellular glutathione content, glutathione export makes no contribution to the establishment of the intracellular thiol redox status.