Silicon nanowires (whiskers) have been grown on Si(lll) via the vapor-liquid-solid (VLS) reaction using silane as the Si source gas and Au as the mediating solvent. The silane partial pressure and temperature ranges were 0.01-1 Torr and 320-600 degrees C, respectively. Growth at high partial pressure and low temperature leads to the growth of Si nanowires as thin as 10 nm. These wires are single crystals but exhibit growth defects such as bending and kinking. Lowering the silane partial pressure leads to an increase in the wire width and a reduction in the tendency to form growth defects. At low pressure, 40-100 nm wide well-formed wires have been grown at 520 degrees C. The VLS reaction using silane allows the growth of Si wires, which are significantly thinner than those grown previously using SiCl4.