Abstract The nature of some of the metabolites present in the cell media from hamster embryo cells that had been grown in the presence of benz[a]anthracene, dibenz[a,h]anthracene and their related K-region epoxides, phenols and cis-dihydrodiols has been investigated. Small amounts of phenols, dihydrodiols and unidentified water-soluble metabolites were detected in the media from the incubations with the hydrocarbons. Benz[a]anthracene 5,6-oxide yielded mainly the related dihydrodiol, whereas dibenz-[a,h]anthracene 5,6-oxide yielded mainly the related phenol and only small amounts of the dihydrodiol. The “K-region” phenols were metabolized to a small extent and both they and the epoxides yielded unidentified water-soluble metabolites. Much of the cis-dihydrodiols were recovered unchanged from the cell media, whereas with the other substrates large proportions of the material originally added to the media were not present in the media at the end of the incubation periods. These results are discussed in relation to those obtained in an examination of the levels of binding of the substrates to the protein, DNA and RNA of the cells that had been grown in the media.