We report the growth of high quality zinc oxide (ZnO) nanowires on  n-type silicon substrates using a physical vapor deposition (PVD) method in two sets of experiments with varying reaction temperatures (800-1200 °C) and growth durations (45 min - 60 min). The diameter of the synthesized nanowires ranged from 50-120 nm with a length of 2-7.1 m. Nanowires had smooth surfaces with relatively uniform diameters. Scanning electron microscope (SEM) studies revealed aggregates of various shapes and dimensions uniformly distributed on the Si substrates. Growth axes of the nanowires were observed to be perpendicular to the surface of the ZnO clusters. These experiments demonstrate the possibility of a simple growth method for such nanowires without the use of any catalysts, thin film deposition or special pre-growth sample treatments hence eliminating any contamination or impurities.