Porous three-dimensional (3D) polyurethane-based biocomposites were produced utilizing diatomite and hydroxyapatite as fillers. Diatomite and Hydroxyapatite (HA) were utilized to reinforce the morphological, chemical, mechanical, and thermal properties of polyurethane foam (PUF). Diatomite and Hydroxyapatite were added into polyurethane at variable percentages 0, 1, 2, and 5. The mechanical properties of PUF were analyzed by the compression test. According to the compression test results, the compressive strength of the polyurethane foam is highest in the reinforced foam at 1% by weight hydroxyapatite compared to other reinforced PUFs. Scanning electron microscopy (SEM) images presented structural differences on foam by adding fillers. Functional groups of PUF were defined by Fourier Transform Infrared Spectroscopy (FTIR) and the thermal behavior of PUF was studied with Thermogravimetric Analysis (TGA). The obtained results revealed that PUF/HA biocomposites indicated higher thermal degradation than PUF/Diatomite biocomposites. The bone can be regarded as a composite substance composed of inorganic minerals mostly formed through hydroxyapatite (HA), which reinforces the bone structure and supplies mechanical strength and moreover an organic matrix consisting of type I collagen. Bone is good at self-regeneration, but the natural healing mechanism is difficult when significant bone loss, so medical implants are generally utilized to overcome the defect of bone. The temporary 3D scaffold, according to the bone tissue engineering approach, plays a significant role in controlling osteoblast functions as well as a fundamental role in guiding the new formation of bone into preferred forms 1. Scaffolds for bone regeneration serve primarily as substrates for binding and proliferation of osteogenic cells. Thus, like bone grafts, three-dimensional biodegradable materials with a porous structure were of big interest not only for their structural and composition similarities to the natural bone but also for their original functional properties, like greater surface area, and high mechanical strength 2. The most studied synthetic biodegradable polymers studied for bone tissue engineering include polylactic acid (PLA), polycaprolactones (PCL), polyglycolide (PGA), and polylactic-co-glycolic acid (PLGA) 3,4. However, when artificial biodegradable polymers are used, the right equilibrium among the rate of tissue regeneration and in vivo degradation is hard to accomplish. For this reason, other polymers, especially polyurethanes, can be utilized to produce scaffolds for the regeneration of bone tissue. The use of polyurethane for scaffolding is probable to achieve a much wider range of morphological and mechanical characteristics compared to mostly used biodegradable polymers 5. Polyurethanes (PU) are classically produced by polyaddition reactions of isocyanates with polyols (polyalcohols). Based on the formulation, a wide property spectrum from elastomer to rigid foams are readily designed and synthesized 6-8. Currently, they are...