Synthesis and radical ring-opening polymerization of bifunctional vinylcyclopropane having a spiroacetal moiety, 1, 10-bis(vinyl)-4,8,12, 15-tetraoxatrispiro [2,2.2.2.2.2]pentadecane (1), were carried out. 1 was prepared by the reaction of 1,1-dichloro-2-vinylcyclopropane and pentaerythritol in DMF in the presence of a base. 1 was isolated by column chromatography as a highly viscous pale yellow transparent oil. Radical polymerization of 1 was carried out in the presence of an appropriate initiator (3 mol % vs 1) at 60, 80, and 120 degrees C in degassed sealed ampules for 20 h. The polymerization mixtures were homogeneous during the polymerizations. Poly(1) was isolated by reprecipitation into ether with a small amount of triethylamine to avoid hydrolysis of the polymer. The crude polymerization mixtures were soluble in chlorobenzene, DMF, and chloroform; however, the polymers after isolation were insoluble in common organic solvents. An incomplete single ring-opening polymerization was confirmed from the analyses of the H-1- and C-13-NMR and IR spectra of the polymer. A double ring-opened unit was not contained in the polymer. The volume shrinkage on the polymerization of 1 with AIBN at 60 degrees C was 4.7%.