New polymerizable liquid crystal materials : 4-(5-Alkyl-1,3-dioxan-2-yl)-phenyl acrylate (7) and 4-(5-alkyl- 1,3-dithiane-2-yl)phenyl acrylates (8) have been synthesized. The corresponding methacrylates were also synthesized. The mesomorphic behavior of these compounds was measured. Though compounds (7) and (7’) exhibit the smectic phase, compounds (8) and (8’) did not exhibit the smectic phase. This must cause by the wider molecular width of compounds (8) and (8’) having two big sulfur atoms. Monomers (7), (7’), (8), and (8’) were polymerized and new liquid crystal polymers were obtained. Though dioxane type polymers (Po-7, Po-7’) exhibited the nematic liquid crystal phase, the corresponding 1,3-dithiane type polymers did not.