Two types of deoxyoligonucleotides, a nona- and two dodecamers have been synthesized as a basis of various aspects in structural and functional studies of the DNA. Using different methodological approaches highly purified deoxyoligomers were obtained and characterized by UV absorption and CD measurements. As an example the results presented are concerned with the synthesis of the following dodecanucleotide containing the recognition site of Hind III : dC-A-C-A-A-G-C-T-T-G-T-G. CD properties and some structural related effects of two complementary and a selfcomplementary deoxyoligomers are described.