Sol-gel method was used to synthetize hydroxyapatite and zinc oxide nanoparticles whose formation and nano structural properties were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FT-IR) techniques. Results confirmed that they possess hexagonal structure containing spherical nanoparticles. Then, HAP/ZnO nanocomposites containing different amounts of ZnO were prepared using cold pressing method at a pressure of 370 MPa, followed by sintering at a the temperature of 1000 degrees C for 3 h in atmospheric air. Their structural properties were investigated using similar techniques. These grain-structured nanocomposites also have hexagonal lattice structure whose crystallinity is reduced through increase in ZnO content. This is while heat-treated pure samples possess the highest crystallinity. Increasing ZnO content in composite samples results in better conglomeration, decrement of the mean size of conglomerated grains and uniform conglomeration size distribution. Pore space study indicates the ability of the composite samples to provide a suitable environment for bone tissue to grow and exchange body fluids. Also, compressive resistance measurement indicates that these samples have compressive strength between 11.48 MPa & 17.43 MPa. Finally, it can be deduced that the sample with 30 wt% ZnO has appropriate properties to replace real bone.