The synthesis of isotactic, syndiotactic and atactic poly(allyltrimethylsilane) (PATMS) is described, along with the characterization of these polymers using thermal methods, X-ray diffraction, solution and solid-state nuclear magnetic resonance (n.m.r). Isotactic PATMS was produced from rac-Me2SiInd2ZrCl2/MAO (methylalumoxane) and displayed chains with an s(3/1) symmetry in the crystalline domains. Syndiotactic PATMS, produced from Me2C(Cp)(Flu)ZrCl2/MAO, was a semicrystalline polymer with chains in the crystalline phase exhibiting s(2/1)2 helical symmetry. A combined X-ray diffraction and solid-state n.m.r. analysis on poorly crystallized samples of syndiotactic PATMS indicates the occurrence in the crystalline phase, for given crystallization conditions, of disorder in the packing of chains, which preserve the helical conformation. Atactic PATMS, an amorphous polymer, was produced using an Ind2ZrCl2/MAO catalyst.