A novel Mg-l.5Zn-0.6Zr-0.2Sc(denoted as ZK21-0.2Sc) alloy was developed as potential biodegradable implant materials.The microstmcture,mechanical properties,and in vitro degradation behavior of the as-cast ZK21-0.2Sc alloy were investigated and compared with ZK21 alloy and pure Mg.The ZK21-0.2Sc alloy showed a single-phase structure with fine equiaxed grains.The alloy exhibited a good balance between strength and ductility.Both immersion tests and electrochemical tests showed that the ZK21-0.2Sc alloy had the lowest degradation rate in Hank’s solution.The excellent degradation behavior of ZK21-0.2Sc alloy could be explained by the single-phase and fine grain structure,the more effective protection corrosion film,and the beneficial alloying effects of Zn,Zr and Sc. A novel Mg-1.5Zn-0.6Zr-0.2Sc (denoted as ZK21-0.2Sc) was developed as potential biodegradable implant materials. The microstmcture, mechanical properties, and in vitro degradation behavior of the as-cast ZK21-0.2Sc alloy were investigated and compared with ZK21 alloy and pure Mg.The ZK21-0.2Sc alloy showed a single-phase structure with fine equiaxed grains. The alloy showed a good balance between strength and ductility.Both immersion tests and electrochemical tests showed that the ZK21 -0.2Sc alloy had the lowest degradation rate in Hank’s solution. The excellent degradation behavior of ZK21-0.2Sc alloy could be explained by the single-phase and fine grain structure, the more effective protection corrosion film, and the beneficial alloying effects of Zn , Zr and Sc.