Synthesis of hyperbranched polycarbosilanes by hydrosilylation of triallylsilane is reported. Soluble high molecular weight polymer was obtained in an uncontrolled bulk reaction. Addition of 2-(10-decen-1-yl)-1,3-oxazoline (i) afforded control over degree of polymerization (DP) and (ii) resulted in hyperbranched macromonomers. 17000 greater than or equal to<(M)over bar (w)>greater than or equal to 800 (GPC (PS)) was obtained. Si-29 NMR spectroscopy allowed identification of dendritic, branched, linear, and terminal silicon branch-points. A modified definition for the degree of branching yielded a value of 0.48 +/- 0.05 (theory: 0.44).