(NHC)Pd/borate initiating systems (NHC = N-heterocyclic carbene) were applied for polymerization of alkyl diazoacetates with a variety of ester groups. The monomers with n-hexyl, cyclohexyl, benzyl, and cholesteryl group as an ester group were transformed into the corresponding poly(alkoxycarbonylmethylene)s with M-n > 10 000. On the other hand, the polymerization of 1-adamantyl diazoacetate afforded low-M-n polymers (M-n < 4000), probably because of steric reasons. Copolymerization of a few comonomer combinations also proceeded successfully to give copolymers with M-n > 20 000.