The controlled/"living＇＇ radical polymerization of n-butyl acrylate (n-BA) and 2-trimethylsilyloxyethyl acrylate (TMS-HEA) by atom transfer radical polymerization (ATRP) is reported. Di- and triblock copolymers with predefined block lengths and low polydispersities were obtained, using methyl 2-bromopropionate as the initiator, (CuBr)-Br-I as catalyst and N,N,N＇,N ",N "-pentamethyldiethylenetriamine as the ligand. Hydrolysis of the trimethylsilyl groups led to block copolymers with n-BA and 2-hydroxyethyl acrylate (HEA) units which were characterized by SEC, H-1 NMR, and DSC. Diblock copolymers of n-BA and HEA could also be obtained by successive addition of the two monomers, in that order. The amphiphilic di- and triblock copolymers formed dispersions in water.