Adult male rats were given orally single doses of ¹⁴ C‐labeled 1,2,3,4‐, 1,2,3,5‐, or 1,2,4,5‐tetrachlorobenzene (TCB) at 10 mg/kg body weight, and were housed in individual metabolism cages to collect urine and feces for radioassay. For 1,2,3,4‐ and 1,2,3,5‐TCB, approximately 46–51% of the doses were excreted in urine and feces within 48 h after administration. During the same period only 8% of the administered 1,2,4,5‐tetrochlorobenzene was excreted. Analysis of urine indicted that the tetrachlorobenzenes were biotransformed to a number of polar compounds. The metabolites for each of the three TCBs in decreasing order of quantities were as follows: 1,2,3,4‐TCB, to 2,3,4,5‐and 2,3,4,6‐tetrachlorophenol and a trace of tetrachlorothiophenol and 2,3,4‐trichloro‐phenol; 1,2,3,5‐TCB, to 2,3,4,6‐tetrachlorophenol, isomeric hydroxythrichlorothiophenols, and a trichlorophenol; 1,2,4,5‐TCB, to 2,3,5,6‐tetrachlorophenol, tetrachloroquinol, and a trichlorophenol.