Anionic polymerization of 2-(1-adamantyl)-1,3-butadiene (1) was carried out either with s-BuLi in cyclohexane at 40 degrees C or with potassium naphthalenide in THF at -78 degrees C. The polymerizations of I quantitatively proceeded to afford the polymers possessing the predicted molecular weights based on the molar ratios between monomers and initiators and the narrow molecular weight distributions. The microstructure of the resulting poly(1) was affected by the initiators and the solvents. The contents of 1,4-repeating unit in poly(1)s obtained with s-BuLi in cyclohexane and with potassium naphthalenide in THF were 96 and 55%, respectively. The 1,4-rich poly(1) was completely converted into a novel saturated alternating copolymer, poly(ethylene-alt-1-vinyladamatttane) (P(E-alt-VAd)), by the hydrogenation with p-toluenesulfonhydrazide. Poly(1) possessing the M-n value over 5000 was hardly soluble in common organic solvents, while the hydrogenated P(E-alt-VAd) was soluble in a wide variety of organic solvents. Novel well-defined block copolymers were anionically synthesized by the sequential copolymerization of 1 and styrene. The results of block copolymerization also demonstrated the living property of the propagating chain end of poly(1). The resulting poly(1) and P(E-alt-VAd) started to decompose from 280 and 380 degrees C in the TGA analyses, respectively. Poly(1) and P(E-alt-VAd) showed T(g)s at 100 and 125 degrees C on the DSC thermograms.