Highly oriented and densely packed one dimensional (1D) polycrystalline Zn nanorods were fabricated on zinc plate without any catalyst at room temperature by bombardment with obliquely incident Ar+ ion via ion irradiation method. The sputtered surfaces were fully covered with Zn nanostructures with diameter and the length around 60 nm and 1.3 urn, respectively, confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The numerical density of Zn nanostructures (nanoneedle or nanorods) was found to be 2.1 × 106 to 9 × 106 /mm2 depends upon the crystal orientation and the atomic density on different crystallographic faces. The outstanding feature of this growth technique is that it provides a new direction for the controllable growth of desired nanostructures of variable density at room temperature without any catalyst. These well-aligned arrays of Zn nanorods/nanoneedle might be a promising material for the future application in nanodevices.