The ring opening metathesis polymerisation (ROMP) of n-alkyl norbornene dicarboxyimides using a wide range of initiators has been extensively studied. ROMP of exo-n-alkyl norbornene dicarboxyimides with classical initiators WCl6/Me4Sn (I) and MoCl5/Me4Sn (II) gave polymers with 63% and 85% trans vinylene content, respectively. In contrast, the endo-isomer could not be polymerised in any of several attempts. Both exo-and endo-n-alkyl norbornene dicarboxyimides were polymerised using well-defined initiators Mo(CH-t-Bu)(N-2,6-i-Pr2C6H3)(OCMe3)(2) (III) and Mo(CHCPhMe2)(N-2,6-i-Pr2C6H3)(OCMe(CF3)(2))(2) (IV). In the case of exo isomers, III gave polymers with 97% trans vinylene content and IV gave polymers with about 30% trans vinylene content. In the case of endo isomer, III gave polymer with 93% trans vinylene content and IV gave polymer with 57% trans vinylene content. The living nature of these polymerisations was confirmed by synthesising AB diblock copolymers by sequential addition of monomers. Both exo- and endo-n-alkyl norbornene dicarboxyimides were also polymerised using well-defined initiator RuCl2(CHPh)(PCy3)(2) (V). The polymers obtained from exo and endo monomers contain 82% and 100% trans vinylene content respectively. The course of the polymerisation reactions using well-defined initiators m-V were followed by H-1 NMR and both the initiator and propagating alkylidenes signals were observable. The multiplicity and broadening of the backbone resonances in C-13 NMR, in all cases, is consistent with a multiplicity of overlapping environments associated with atactic microstructures.