Being biocompatible and biodegradable, magnesium alloys are considered as the new generation biomedical implant materials, such as for stents, bone fixtures, plates and screws. A major drawback is the poor chemical stability of metallic magnesium; it corrodes at a pace that is too high for most prospective implant applications. Requirements for biodegradable implants are bio-compatibility, controlled biodegradability and sustainable mechanical properties. Various magnesium alloys containing Al, Zn, Y and rare-earth elements are analyzed in this respect. The alloys are compared on the basis of microstructure, tensile tests and potentio-dynamic polarization tests in simulated body fluid. The effects of semi-solid processing, hot extrusion, heat treatments and sterilization on corrosion resistance and tensile properties are investigated. AZ80 magnesium alloy with certain post-processing treatments fulfills the requirements best as a prospect implant material which has the potential for further improvement by trace alloying additions and surface modifications.