Hepatic GSH is utilized in conjugation reactions with the chemically-reactive metabolite, thus its measurement is a useful indication of the extent of conjugation. The toxic effect of allyl alcohol on rat livers is related to its conversion into acrolein. The toxicity of acrolein could be related to further metabolic activation into acrilic acid and/or glycidaldehyde. Allyl alcohol may also be converted into glycidol. Since hepatic GSH is an important determinant of allyl alcohol hepatotoxicity, we have studied "in vitro" reactivity of GSH with allyl alcohol, acrolein and glycidol. The addition of these chemicals to incubation mixtures containing liver 105.000 g supernatant fraction, phosphate buffer and GSH leads to GSH consumption, as measured by the Ellman's method. All the compounds examined react with GSH when added to incubation mixtures containing or no SPM. These results seem to indicate that these chemicals react with glutathione either enzymatically or no.