Poly(vinyl acetate) and poly( vinyl propionate) star polymers with four arms were produced via reversible addition fragmentation chain transfer (RAFT) polymerization, employing a tetra-functional xanthate as the RAFT agent, in which the stabilizing groups are linked to the core. These novel star-like RAFT agents induced living/controlled behavior in both the vinyl acetate polymerization at 60 degreesC and in the vinyl propionate polymerization at 90 degreesC, respectively, leading to star polymers with minimum polydispersities of 1.2 and maximum apparent number average molecular weights of about 50,000 g . mol(-1). The microstructure of the star polymers was confirmed by electrospray ionization mass spectrometry.