DNA fragments can be immobilized by Langmuir - Blodgett films of 1-hexadecylamine. The inclusion in these LB films of 5′-GTAAAACGACGGCCAGT-3′ was proved by a radioactive technique. An X-ray diffraction study proved an overall lamellar ordering of the samples and suggested a structural organization in which layers of oligonucleotide molecules are sandwiched between two monolayers of 1-hexadecylamine. These monolayers are likely to turn their amino groups surfaces to the oligonucleotide molecules as to screen their anionic charges.