Hyperbranched methacrylates were synthesized by self-condensing group transfer polymerization (SCGTP) of 2-(2-methyl-1-triethylsiloxy-1-propenyloxy)ethyl methacrylate (MTSHEMA) and characterized by multidetector SEC and C-13 NMR. Depending on the reaction conditions, molecular weights up to M-w = 38 000 at a polydispersity of M-w/M-n approximate to 3.8 could be obtained. Kinetic measurements showed that cyclization, i.e., the intramolecular reaction of a functional group with the polymer's vinyl group, limits the molecular weights and lowers the polydispersity. A maximum degree of branching of DB approximate to 0.4 and a reactivity ratio of the propagating and initiating groups in the range of 13 < r < 23 were determined. Slow addition of MTSHEMA to the monofunctional initiator, 1-methoxy-3-(trimethylsilyloxy)-2-methyl-1-propene (MTS), enabled the control of molecular weights and decreased the polydispersity to M-w/M-n approximate to 2.8. The addition of methyl methacrylate (MMA) to a living MTSHEMA core yielded a "hyperstar" polymer.