Tissues from beagle dogs fed Terraclor in food (PCNB, daily for up to two years) were analyzed by gas chromatography for residual PCNB, impurities, and metabolites. The data obtained are indicative that PCNB is not present in fat or tissue and the metabolic products of PCNB are pentachloroaniline (PCA) and methyl pentachlorophenyl sulfide. The presence of PCA and methyl pentachlorophenyl sulfide has been established by infrared and mass spectroscopy. Chromatographic analyses of extracts of rat tissues from rats fed PCNB and from plants grown in PCNB treated soil are indicative of an identical metabolism. © 1969, American Chemical Society. All rights reserved.