A study of the monomer-isomerization polymerizations of 2-heptene and 3-heptene has been investigated with (C2H3)3Al-TiCl3catalyst at 80°C. It was found that 2-heptene and 3-heptene underwent monomer-isomerization polymerization to give a high molecular weight polymer consisting of 1-heptene units. In these polymerizations the isomerization of both olefinic monomers was observed. The addition of the isomerization catalyst nickel acetyl-acetonate [Ni(acac)2] accelerated these polymerizations. The rate of polymerization of heptene isomers decreased in the following order; 1-heptene ≧ 2-heptene > 3-heptene. The rate of polymerization and the isomer distribution of unreacted olefinic monomer after polymerization occurred via a stepwise double bond migration mechanism. It was also found that the monomer-isomerization copolymerization occurred between trans-2-butene and 2-heptene to give a copolymer cosisting of 1-butene and 1-heptene units. From the results of this copolymerization, the apparent monomer reactivity ratios were obtained as r1= 1.45 ± 0.05 and r2= 0.50 ± 0.10, whereM1is trans-2-butene and M2is 2-heptene.