<p>In this research, the effect of alloying element of Al and plasma nitriding temperature on microstructure, tensile, and in vitro corrosion properties of biocompatible Mg-Al-Ti alloy was studied. Based on microstructural observation, with an increase in Al content, the volume fraction of Mg₁₂Al₁₇ intermetallic phase increased. By increasing the Al content, the grain size decreased. Also, plasma nitriding resulted in the generation of compressive residual stress near the treated surface. As the nitriding temperature increased, the thickness of the nitride layer and compressive residual stress increased. Furthermore, with an increase in Al content, the strength of alloys increased as a result of precipitation and grain refinement strengthening mechanisms. However, by increasing the temperature of plasma nitriding, both strength and elongation grew due to the generated compressive residual stress. The strength of the alloy with 8 wt% Al after nitriding at 698&#xa0;K increased from 241&#xa0;MPa in the untreated alloy to 253&#xa0;MPa. Furthermore, the corrosion resistance of alloys in Hank’s solution decreased with Al content because of galvanic corrosion near the interface of precipitates. In contrast, corrosion resistance improved with plasma nitriding temperature as a result of the formation of a dense nitride layer, growth of the nitride layer, and generation of higher compressive residual stresses.</p>