2′-O-(2,3-Dihydroxypropyl)arabinouridine-containing oligodeoxyribonucleotides were synthesized starting from a new modified nucleoside, viz., 2′-O-(2,3-dihydroxypropyl)arabinouridine, and the corresponding 3′-phosphoramidite. Oxidation of these oligodeoxyribonucleotides with sodium periodate afforded oligonucleotides containing 2′-O-(2-oxoethyl)arabinouridine residues. Subsequent modification of the aldehyde-containing oligonucleotides involved the reactions with 9-hydrazinoacridine and N-aminooxyacetyl peptide and reductive amination by 4-(1-pyrenyl)butyrohydrazide and biotin hydrazide. Thermal stabilities of duplexes of modified oligodeoxyribonucleotides with complementary oligodeoxyribonucleotides are slightly lower than those of natural duplexes. Duplexes with complementary oligoribonucleotides are substantially destabilized.