Abstract: The effect of extrusion temperature and ratio on the microstructure, hardness, compression, and corrosion behavior of Mg–5Zn–1.5Y alloy were analyzed in this study. The microstructural observations revealed that the cast alloy consists of α-Mg grains, and Mg₃Zn₆Y and Mg₃Zn₃Y₂ intermetallic compounds, mostly located on the α-Mg grain boundaries. Extruded alloy at higher temperatures showed coarser grain microstructures, whereas those extruded at higher ratios contained finer ones, although more dynamic recrystalized grains with lower intermetallics were measured at both conditions. Combined conditions of the lower temperature (340°C) and higher ratio (1:11.5) provided higher compressive strengths. However, no significant hardness improvement was achieved. The extrusion process could decrease the corrosion rate of the cast alloy in simulated body fluid for over 80% due to primarily the refined microstructure. The extrusion temperature showed a more pronounced effect on corrosion resistance compared to the extrusion ratio, and the higher the extrusion temperature, the higher the corrosion resistance.