Diethyl (Z,Z)-muconate (EMU), di(benzylammonium) (Z,Z)-muconate, and its chlorosubstituted derivatives are highly susceptive to gamma -irradiation and polymerize in high yields in the crystalline state. gamma -Radiation polymerization produces the same stereoregular polymer consisting of meso-diisotactic-2,5-trans-repeat unit, as that obtained by photopolymerization in the crystalline state. The polymer yield increases with an increase in a radiation dose, but the resulting polymer decomposes during gamma -irradiation at high radiation doses. The effects of the radiation dose rate and the postpolymerization on the polymer yield were negligible for the gamma -irradiation polymerization at room temperature, while the polymer yield decreased with the decrease in the crystal size and the polymerization temperature. The single-crystal structure analysis of the polymer crystal confirmed the topochemical polymerization process of the gamma -radiation polymerization.