ZnO nanostructures were grown by pulsed laser deposition on c-plane sapphire substrates. The as-grown nanostructures were examined by scanning electron microscopy and transmission electron microscopy ZnO nanowires were grown using a gold catalyst, at a high substrate temperature of 800°C and an ambient gas pressure of 0.5 mbar (5% oxygen, 95% argon). Changing the gas composition to pure oxygen led to the growth of stacking fault-free ZnO nanosheets with their growth direction inclined to the  direction. Similar nanosheets with stacking faults were found when lowering the growth temperature to 600°C for a 5% oxygen – 95% argon ambient gas composition and the same overall pressure. A growth mechanism for these ZnO nanosheets is proposed.