One of the significant challenges in bone tissue engineering, is the fabrication of highly porous scaffolds (?80%) with interconnected pores and appropriate mechanical strength. Commonly available synthetic scaffolds made of ceramic or polymer but a better combination of properties can be achieved with a composite or multi-component structure. Using composites is a method to take advantage of both polymer and ceramic qualities, ideally to achieve materials with high stiffness and high toughness. Among the bioceramics used for tissue engineering scaffolds, bioactive silicate ceramics such as diopside (Dp) and bredigite (Br) have been paid much attention in recent researches. Dp and Br have high mechanical and bioactivity properties, excellent biocompatibility, and appropriate degradation rate. In addition to, it is recognized that the degradation products of them in physiologic fluids, such as Si, Ca, and Mg, could promote the proliferation and differentiation of osteoblast cells. Despite the benefits mentioned for Dp and Br, there are few articles about building their scaffolds. Considering benefits of nanostructure bioceramics, in this study efforts were focused on the fabrication of nanostructure Dp/Br composite scaffolds by using gelcasting and space holder methods. For this purpose, Dp and Br nanopowders were synthesized by the sol-gel and mechanical alloying methods and nanocomposite scaffold were prepared on addition of B r to pure Dp, in proportion of 0, 25, 50, 75, and 100 wt.% . The prepared scaffolds were finally coated with 0, 2.5, 5, 7.5, and 10 wt.% gelatin soulution to improve their toughness and compressive strength. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Transmission electron microscopy (TEM) were used to characterize and evaluate the phase structure, crystallite size, morphology, size and distribution of the pores, chemical composition and particle size of the prepared powders and composite scaffolds. The porosity of the scaffolds was measured by Archimedes method. The compressive tests were performed on samples consisting of cylindrical bars with a crosshead speed of 0.5 mm/min. Fourier transform infrared spectroscopy (FTIR) was used to study the structure of gelatin coating befor and after crosslinking. To evaluate the bioactivity and bioresorbability, the scaffolds were immersed in the simulated body fluid (SBF) for 28 days. The concentration of the Mg and P ions in the filtered solutions were determined by inductive coupled plasma optical emission spectroscopy (ICP-OES). FTIR, XRD, EDS and SEM were used to investigate the bone like apatite formation on the surface of the scaffolds and pores filling by formation of apatite. The viability, proliferation, and adhesion of cells and also the alkaline phosphatase activity were determined by culturing Saos-2 cells on the scaffolds for 1, 3 and 7 days. The results showed that the scaffolds have a crystallite size smaller than 40 nm. NaCl spacer showed a uniform porous structure with open spherical pores (400-600 µm), as compared with NH 4 HCO 3 spacer which showed an irregular pore morphology (150-400 µm). On the other hand, the scaffolds prepared by gelcasting method showed a wide range of pore size distribution (200-800 µm). The prepared nanostructure Dp/Br composite scaffolds had a highly porous structure (83-86%) with 80-84% open porosity. Polymer coating with 5 wt.% gelatin solution led to a 3- to 3.4-fold increase of the compressive strength and 5.7- to 7.7-fold increase of the toughness while reducing the total porosity was about 7%. In addition, polymer coating with 2.5 wt.% gelatin solution led to a 1.9- to 2.2-fold increase of the compressive strength and 3.2- to 3.7-fold increase of the toughness while reducing the total porosity was about 4%. The compressive strength of the prepared scaffolds with total porosity more than 70% was in the range of 0.98-4.62 MPa, which was in the range of the compressive strength of the spongy bone. . The novel nanostructure composite scaffolds described in this study seems to be suitable for bone repair and regeneration in bone tissue engineering. Keywords : Diopside; Bredigite; Gelatin; Gelcasting; Space holder; Scaffold; Nanocomposite; porosity; Mechanical properties; tissue engineering.