The hydroxylamine derivative of misonidazole reacts with glutathione under physiological conditions to form two isomeric conjugates. Based on physical and chemical properties, the two conjugates have been identified as 1-[2-amino-(4-glutathion-S-yl)-1-imidazolyl]-3-methoxypropanol and 1-[2-amino-(5-glutathion-S-yl)-1-imidazolyl]-3-methoxypropanol. The formation of the glutathione conjugates of reduced misonidazole offers a molecular mechanism for the depletion of GSH in mammalian cells after exposure to misonidazole under hypoxic conditions.