In an attempt to clarify the protective action of an antioxidant agent against acute toxicity of thioacetamide (TAA) and in order to throw some light on an satisfying concept of the mechanism of its action, a single dose of alphatocopherol (200 mg per kg) was given orally by stomch tube to male mice prior to the administration of thioacetamide in a dose of 200 mg per kg of body weight. Sections of liver samples, obtained from the mice which were sacrificed at intervals of 3, 6, 9, or 12 hours after TAA administration, were stained using the methyl green-pyronin technique.