By using a catalyst-assisted vapor phase deposition method, we recently fabricated high-quality ordered ZnO nanorod arrays with uniform rod size. The rods, grown perpendicularly on GaN/Al2O3 substrates, were [0001]-oriented single crystals with diameters of 200 nm, length of 4.7 μm, and rod-to-rod spacings of 500 nm. The growth conditions, including the choice of the substrate, the patterning of the catalyst on the substrate, and the growth parameters, played important roles in determining the morphology of the rods, and the best samples were produced under optimized conditions. Time-resolved micro-photoluminescence measurements on single nanorods demonstrated laser emission at temperatures up to room temperature. These high-crystal-quality nanorod arrays may be promising candidates for ultraviolet nanolaser arrays.