The multifunctional monomers 5＇-methacryloyluridine and 5＇-methacryloyladenosine have been polymerized under atom transfer polymerization conditions, giving products of narrow polydispersities as consistent with living polymerization. Initiators derived from both uridine and adenosine have also been used to terminally functionalize poly(methyl methacrylate) and poly(styrene). Both hydroxyl-protected and unprotected initiators successfully gave polymers of predictable and narrow PDI. Atom transfer polymerization of methyl methacrylate with the protected 5＇-bromoisobutyroyluridine initiator 2 with NMPI ligand in conjunction with copper(I) bromide gives polymer with an M-n of 13 100 with a very narrow PDI of 1.06 (M-n of 11 000 H-1 NMR). The initiator efficiency is less than unity (e.g., 0.81 for the above reaction), similar to that observed with nonfunctional initiators. 1H NMR is used to demonstrate the presence of the initiator in the polymer. The results demonstrate that this living polymerization system is inert to a multitude of functionality in the initiator, including secondary hydroxyl, silyl ether, tertiary amine, primary amine, secondary amide, etc. Atom transfer polymerization has been used to synthesize well-defined poly(nucleoside)-based polymers which have tremendous potential for templating and polymers used in applications that require biorecognition.