Homopolymers of 2-(dimethylamino) ethyl methacrylate ( DMAEMA) have been synthesized directly in aqueous media by reversible addition-fragmentation chain transfer polymerization ( RAFT) using 4,4'-azobis(4-cyanopentanoic acid) (V501) as a water-soluble azo initiator and 4-cyanopentanoic acid dithiobenzoate (CPADB) as a chain transfer agent. The resulting polymers were controlled in the range of narrow molecular weight distributions, with (M) over bar (w)/(M) over bar (n) lower than 1.3. Using the produced dithioester-capped DMAEMA homopolymer as a macro chain transfer agent, miniemulsion RAFT polymerization of methyl methacrylate and styrene were carried out, respectively. H-1 NMR analysis showed that the diblock copolymer PDMAEMA-b-PMMA in the form of stable latices was obtained as expected.