2'-Deoxyoxanosine (dOxo) is a novel DNA lesion produced from 2'-deoxyguanosine by the reaction with nitrous acid or nitric oxide. We found that dOxo reacted with glycine under physiological conditions. The product was identified by spectrometric data as an adduct between the six membered ring of dOxo and an amino group of glycine. The adduct was more stable than dOxo under physiological conditions. The incubation of an oligodeoxynucleotide containing dOxo with glycine gave also rise to the adduct. These results suggest that dOxo formed in DNA reacts with amino groups of various compounds around DNA in vivo resulting in the adduct.