The metabolism of C14-d-α-tocopheryl quinone (α-TQ) and its hydroquinone (αTHQ) was investigated. Forty-six hours after intraperitoneal administration of either compound to rats the radioactivity isolated from the liver was present almost exclusively in C14-α-TQ. The results indicated, however, that in situ this compound was present primarily in the reduced form. No conversion to C14-α-tocopherol or other liver metabolites was observed. α-THQ was eliminated from the tissues more rapidly than α-TQ. The main metabolite excreted in the urine was a conjugate of α-tocopheronic acid and the main metabolite excreted in the feces was a conjugate of α-TQ. Free C14-α-TQ was present in the feces after administration of this compound but not after C14-α-THQ administration.