Addition polymerization and copolymerization of bis(Me 3Si)-substituted norbornene-type monomers such as 5,5-bis(trimethylsilyl)norbornene-2, 2,3-bis(trimethylsilyl)norbornadiene-2,5 and 3,4-bis(trimethylsilyl)tricyclo[4.2.1.0 2,5]nonene-7, in the presence of Ni(II) naphtenate/MAO catalyst were studied. Disubstituted norbornene and norbornadiene were found to be practically inactive in homopolymerization. On the other hand, their copolymerization with norbornene proceeded with moderate yields of copolymers containing predominantly norbornene units. Under studied reaction conditions 2,3-bis(trimethylsilyl)norbornadiene-2,5 was transformed into the only exo-trans-exo-dimer as a result of the [2+2]-cyclodimerization reaction. Moving Me 3Si-substituents one carbon atom away from norbornene double bond made 3,4-bis(trimethylsilyl)tricyclo[4.2.1.0 2,5]nonene-7 active in homopolymerization and allowed to obtain addition homo-polymer with two Me 3Si-substituents in each elementary unit. The reaction mechanism and steric effect of Me 3Si-substituents are also discussed.