Nano-crystalline Au (n-Au) prepared by gas deposition method has been compared with vapor deposited (v-Au), fine powder and polycrystalline Au by positron lifetime spectroscopy. Dislocations, vacancies, grain boundaries, micro-voids at intersections of grain boundaries, and surface trapping sites have been measured depending on the samples and on the condition of heat treatments. Other techniques, scanning tunneling microscopy and hardness measurement, were also used for comparison. It has been shown that small vacant sites with the size corresponding to micro-voids are left in n-Au and, to a lesser extent, in v-Au at high temperatures at which all the vacancies would have been annealed out in normal polycrystals.