[en] Special analytical methodology was developed for purification of 4-chloro[¹⁴C]benzotrichloride, which is both volatile and hydrolytically unstable at milligram mass levels. When rats were given a single oral dose of 4-chloro[¹⁴C]benzotrichloride at 1.5 mg/kg, within 4-6 days 87 and 9% of the applied ¹⁴C were excreted in urine and feces, respectively. The major urinary metabolite was identified as 4-chlorohippuric acid, representing 78% of the applied dose. While about two-thirds of the fecal ¹⁴C residues were unextractable with organic solvents, free 4-chlorobenzoic acid and α,α,4,4'-tetrachlorostilbene contributed 10 and 8% of the fecal ¹⁴C. The metabolic production of α,α,4,4'-tetrachlorostilbene appears to occur by a novel metabolic pathway