Glutathione depletion either decreased or increased death‐receptor–mediated apoptosis in previous studies. Comparison of the durations of glutathione depletion before death‐receptor stimulation in these studies might suggest a different effect of prolonged versus acute thiol depletion. We compared the effects of the prolonged glutathione depletion caused by a sulfur amino acid–deficient (SAA⁻) diet and the acute depletion caused by a single dose of phorone on hepatic apoptosis triggered by the administration of an agonistic anti‐Fas antibody. The chronic SAA⁻ diet did not affect hepatic Fas or Bcl‐XL, but increased p53 and Bax, and exacerbated Fas‐mediated mitochondrial membrane depolarization, electron‐microscopy–proven outer mitochondrial membrane rupture, cytochrome c translocation to the cytosol, and caspase 3 activation. These effects were prevented by cyclosporin A, an inhibitor of mitochondrial permeability transition. The SAA⁻ diet increased internucleosomal DNA fragmentation, the percentage of apoptotic hepatocytes, serum alanine transaminase (ALT) activity, and mortality after Fas stimulation. Despite a similar decrease in hepatic glutathione, administration of a single dose of phorone 1 hour before the anti‐Fas antibody did not change p53 or Bax, and did not enhance Fas‐induced mitochondrial permeability transition and toxicity. However, 4 repeated doses of phorone (causing more prolonged glutathione depletion) increased Bax and Fas‐mediated toxicity. In conclusion, a chronic SAA⁻ diet, but not acute phorone administration, increases p53 and Bax, and enhances Fas‐induced mitochondrial permeability transition and apoptosis. Thiol depletion could cause oxidative stress that requires several hours to increase p53; the latter induces Bax, which translocates to mitochondria after Fas stimulation.