DNA adducts induced by putative chemical related to carcinogenesis were detected and determined by (32)^P-Postlabelling assay after exposure of 4 compounds comprising two azo dyes (amaranth, new coccine) and two flavonoid compounds (rutin, quercetin) to ICR mouse. DNA was isolated from mouse liver and digested enzymatically to deoxyribonucleoside 3`-monophosphate. The postincubation of DNA digests with nuclease P1 before (32)^P-labelling enhanced the technique`s sensitivity. Nuclease P1 cleaves deoxyribonucleoside 3`-monophosphates of normal nucleotides to deoxyribonucleosides which do not serve as substrates for polynucleotide kinase, while most of adducts were found to be totally or partially resistant to the 3`-dephosphorylating action of nuclease Pl. The adducted deoxyribonucleoside 3`-monophosphate was converted to 5`-(32)^P-labelled deoxynucleoside 3`,5`-bisphosphate by T4 polynucleotide kinase. The nucleotides were separated by anion-exchange thin layer chromatography(TLC) on polyethyleneimine cellulose by 4-dimensional or 2-dimensional TLC then detected by autoradiography. The results show that DNA adducts were detected in liver DNA of ICR mouse after administration of amaranth and quercetin by 2-dimensional and/or 4-dimensional TLC.