The Servacel DHB (m-dihydroxyborylphenylaminoethyl cellulose) chromatographic procedure developed by Sawiki et al. (Cancer Res., 43, 3212-3218, 1983) for analysis of 7,12-dimethylbenz[a]anthracene (DMBA)-DNA adducts was applied to analyze syn- and anti-1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydro-5-methylchrysene (DE-I)-deoxyribonucleoside adducts. Identical elution conditions to whose developed for the DMBA adducts were employed. While the results were similar to those obtained in the DMBA system, some of the anti-DE-I-deoxyribonucleoside adducts eluted with the buffer system used for elution of syn-adducts. Complete resolution of the anti- and syn-adducts was obtained when modified elution conditions as developed by Pruess-Schwartz et al. (Cancer Res., 44, 4104-4110, 1984) for analysis of syn- and anti-7α-8β-dihydroxy-9β, 10β-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene-DNA adducts were applied. Based on this chromatographic procedure about 15% of the DE-I deoxyribonucleoside adducts, formed in mouse skin DNA upon treatment with 5-[3H]methylchrysene (MeC), originated from syn-DE-I.