3-Hydroxychrysene, a metabolite of the polycyclic aromatic hydrocarbon (PAH) chrysene, was metabolised by rat liver microsomal preparations obtained from Arochlor 1254-pretreated rats. Eight major metabolites were isolated by high performance liquid chromatography and characterised by u.v. spectroscopy and a variety of mass spectrometric techniques. The metabolites were unambiguously identified as 9-hydroxy-trans-1,2-dihydroxy-1,2-dihydrochrysene and 9-hydroxy-r-1,t-2,t-3,c-4-tetrahydroxy-1,2,3,4-tetrahydrochrysene and tentatively identified as 3-hydroxy-trans-5,6-dihydroxy-5,6-dihydrochrysene (since chrysene is a symmetrical molecule the 3- and 9-positions are equivalent), 9-hydroxy-trans-3,4-dihydroxy-3,4-dihydrochrysene, 1,2,3-trihydroxy-1,2,3,4-tetrahydrochrysene, an oxidised phenol and two diphenols. These results indicate that 3-hydroxychrysene can be further metabolised via a number of different pathways including those involving the formation of phenol- and triol-epoxides.