Organic thin films in which DNA double strands aligned in one direction were prepared by two methods : 1) polyion complexes of DNA anions and cationic amphiphiles was prepared and the organic solution of the DNA-lipid complex was cast and the obtained transparent film was stretched in one direction, and 2) DNA anions were solubilized in subphase with intercalated dyes and were transferred with cationic lipid monolayers by vertical dipping method. DNA strands could be aligned along stretching direction in the cast film and along dipping direction in the LB film. The orientation of DNA strands in the thin films were confirmed by X-ray diffraction and polarized absorption spectra.