Biodegradable materials hold great promise for next-generation implants that will replace current permanent non-degradable implants, such as orthopedic fixation devices, cardiovascular stents, etc. The principle is that the implants degrade harmlessly in the body over time as new tissues grow, which eliminates the need for secondary surgeries and associated costs. Recent research on biodegradable polymers and metals have demonstrated their potentials for clinical translations, but there are still major challenges yet to be addressed, e.g. (1) how to regulate their degradation rate to match tissue healing rate, and (2) how to control their bioactivity to promote healing functions of desirable cells while inhibiting infectious functions of bacteria. In this presentation, our recent progress on developing magnesium (Mg) alloys as the next-generation biodegradable implant materials, and creating new surface modification strategies and biodegradable composites to regulate their degradation rate, will be discussed. Specifically, in vitro degradation of Mg-Zn-Sr alloy based intramedullary pins, their cytocompatibility with bone marrow derived mesenchymal stem cells (BMSCs), and the in vivo degradation and associated host responses in rat tibiae will be reported.