A significant challenge in bone tissue engineering is the development of 3D structures serving as a scaffold to fill the bone defects, support bone-forming cells, and promote bone regeneration. Due to the similarity in the chemical composition with bone apatite components, hydroxyapatite (HA) scaffolds have been widely applied as bone substitute. However, low mechanical properties and degradation rate of HA have led to development of novel bioceramics and composites with improved properties compared to pure HA. Results confirmed that the mechanical, Physical and biological properties of HA porous scaffolds could be modified using the addition of suitable secondary components. CaO-SiO 2- MgO bioceramics demonstrated high bioactivity and good mechanical properties. Diopside is a Ca, Si and Mg-containing bioceramics. Results showed that Ca-Si-Mg containing bioceramics not only possessed an improved mechanical strength when compared to HA and ceramics, but also were degradable. The aim of this study is to develop three-dimensional HA-diopside porous scaffolds using space holder technique. HA and diopside nanopowders were synthesized via sol-gel and combustion sol-gel respectively, and then various ratios of HA and diopside nanoparticles (5, 10 and 15 wt. % diopside) were mechanically combined. Then, after addition of poly vinyl alcohol (PVA) and sodium chloride as space holder, they compacted using compression. In order to sinter the compacted powders, remove sodium chloride and PVA powders and develop porous structure, samples were heat treated at 1350 ?cfor 2h. X-ray diffraction (XRD) technique was utilized to confirm presence of the desired phases in the structure and also, to determine the crystallite of the prepared scaffolds. The crystallite sizes were calculated by Scherrer and modified Scherrer equation and the results were compared. To evaluate the shape and size of the particles and crystallites, a transmission electron microscopy (TEM) was applied and the size of HA and diopside nanopowder particles was calculated. Scanning electron microscopy (SEM) was applied in order to study morphology and surface of nanopowders and scaffolds before and after soaking in simulated body fluid (SBF). Energy dispersive X-ray spectroscopy (EDS) was utilized to evaluate the chemical composition and distribution of elements in scaffolds. Furthermore, axial compression test was applied to study the mechanical properties of scaffolds. Bioactivity of different scaffolds was investigated by soaking them in SBF for various periods (14 and 28 days). The concentration of calcium and phosphorus ions in SBF and the content of pH of SBF were determined for various periods by ICP-OES method and pH meter, respectively. Results showed that composite scaffolds with pore sizes in the range of 200-340 ?m, appearance porosity of 76-82 (%) and compressive strength of 1.2-3.2 (MPa) were developed. SEM images of scaffolds after soaking in SBF depicted the tiny agglomerated bone-like apatite particles. Also, biocompatibility evaluations by MTT method showed that scaffolds could stimulate cell proliferation of Osteoblast-like cells and they did not have any cytotoxicity, as compared to control sample. Considering the results obtained, it seems that, manufactured scaffolds could be a good candidate for bone tissue engineering. Keywords : Porous materials, Hydroxyapatite, Diopside, Mechanical properties, Biocompatibility