Self-complementary decadeoxyribonucleotides containing alpha-putrescinyl-thymidine (Put Thd), AAGAATTPCTT, AAGAATTCTPT, AAGAATTPCTPT, (p is the abbreviation of alpha-putrescinyl residue) were prepared by the phosphotriester method. Nuclease activities and Tm for their oligomers were investigated by comparison of AAGAATTCTT.