The relationship between the microstructure and the properties of poly(1,3-cyclohexadiene)s, obtained by living anionic polymerization with an alkyllithium/amine system, and their hydrogenated derivatives are reported. The 1,2-bond/1,4-bond molar ratio of poly(1,3-cyclohexadiene) was determined by measuring BD-NMR with the H-H COSY method. The glass transition temperature of poly(1,3-cyclohexadiene) was found to rise with an increase in the ratio of 1,2-bonds to 1,4-bonds or with an increase of the number average molecular weight. The 1,2-bond of the polymer chain gives a high flexural strength and heat distortion temperature. Hydrogenated poly(1,3-cyclohexadiene) has the highest T-g (231 degrees C) among all hydrocarbon polymers ever reported. 1,3-Cyclohexadiene-butadiene-1,3-cyclohexadiene triblock copolymer and 1,3-cyclohexadiene-styrene-1,3-cyclohexadiene triblock copolymer have high heat resistance and high mechanical strength.