Purine deoxyribonucleoside 3'-phosphates were reacted with the (+)- and (-)-enantiomers of the anti dihydrodiol epoxide of benzo[a]pyrene. Products from cis and trans opening of the epoxide ring were separated by HPLC and they were identified by comparison of their CD spectra with those known for the corresponding nucleoside adducts. Thereafter, the eight known benzo[a]pyrene-purine deoxyribonucleoside-3'-phosphate adducts were postlabeled with [32P]ATP and T4 kinase and the positions of these individual bisphosphates were mapped by TLC. Though all eight adducts migrated to the same general region of the thin layer plates, the four possible adducts from each enantiomeric dihydrodiol epoxide were resolved.