DNA adduct formation in vivo in mouse skin following a single topical application of benzo[a]fluoranthene (BbF), benzo[j]fluoranthene (BjF), benzo[k]fluoranthene (BkF), or indeno[1,2,3-cd]pyrene (IP) was investigated in female CD-1 mice using 32P-postlabeling analysis. Distinct adduct profiles were detected for each of the non-alternant hydrocarbons examined. Two adducts, one major and one minor, were detected using polyethyleneiminecellulose (PEI-cellulose) thin-layer chromatography (TLC) for BbF and BjF while a single major adduct was detected for BkF and IP. The relative extent of binding to mouse skin DNA was in the order BbF greater than BjF greater than BkF greater than IP. 32P-Postlabeled DNA adducts separated by PEI-cellulose TLC were further analyzed by high performance liquid chromatography (HPLC). A single radioactive peak was detected for 32P-labeled DNA adducts of BjF and BkF. Three general areas of radioactivity were detected when 32P-labeled DNA adducts of BbF were separated on HPLC.