- Nanocomposites of AZ31B with varying compositions of nano-hydroxyapatite and nano alumina were cast by the stir casting process. The primary goal of this research is to investigate and assess if it is feasible to fabricate magnesium metal matrix nano-composites (MMNCs) utilizing the stir casting process for biomedical applications. In this study AZ31B used as matrix and nano alumina (Al2O3) and nano hydroxyapatite (nHA) as a reinforcement. Due to its low weight as a structural metal and excellent strength-to-weight ratio, magnesium is commonly employed in engineering designs in addition to the development of composite materials. Mg alloys are widely used in biomedical due to their lower density. The Brinell hardness test was conducted to examine materials made by casting and forging processes that have a structure which is too coarse or rough for another test. It was observed that AZ31B-5nHa among the others has the highest hardness number. Compression tests were conducted to check the behavior of the MMNC under an applied load. AZ31B-0.5(Al2O3)-0.3nHa among the others has the highest compressive strength. It was observed that adding nHA reinforcement in AZ31B affects the microstructure and mechanical characteristics of a nanocomposite made of magnesium metal matrix, including compressive strength, hardness, corrosion resistance and biocompatibility. This study aims to investigate the effects of reinforcement on a magnesium metal matrix nanocomposite's microstructure and mechanical properties. © 2022 Elsevier Ltd