Rabbits and rats dosed with 1,2-epoxy-3-phenoxypropane excrete 2-hydroxy-3-phenoxypropionic acid and N-acetyl-S-(2-hydroxy-3-phenoxypropyl)-L-cysteine. 2. Rabbits and rats dosed with 1,2-epoxy-3-(p-nitrophenoxy)propane excrete 2-hydroxy-3-(p-nitrophenoxy)propionic acid, N-acetyl-S-[2-hydroxy-3-(p-nitrophenoxy/propyl)propyl]-L-cysteine and p-nitrophenol. 3. The administration of either epoxide to the rat produces a marked fall in hepatic GSH level. 4. The biliary excretion of metabolites of 1,2-epoxy-3-(p-nitrophenoxy)-propane is described.