A new type of nucleic acid analogs with polysiloxane backbones is reported in this paper. Four new organosilicon monomers containing nucleic acid bases or 5-fluorouracil, i.e., γ-(N1-uracilyl) propylmethyldiethoxysilane (1), γ-(N1-thyminyl) propylmethyldiethoxysilane (2),γy-(N9-adenyl) propylmethyldiethoxysilane (4) anr-(N15-fluorouracilyl) propylmethyldiethoxysilane (3), were prepared by the alkylation of γ-bromopropylmethyldiethoxysilane with uracil, thymine, adenine and 5-fluorouracil, respectively. The polymerization of these monomers,in-cluding the copolymerization of (1) with diacetoxydimethylsilane (5),or 1,3-bis (acetoxy-1,1,3,3-tetramethyldisiloxane (6),were carried out under different conditions. Thus,a variety of ho-mopolymers and copolymers were obtained with polysiloxane structure as the main chain and nucleic acid base as the pendant group. The monomers and polymers were structurally identi-fied by 1H-NMR,IR.UV and elemental analysis. The [n] and Mn of the polymers were also determined.