In the scope of this study, AZ31 and AZ91 magnesium alloys are to be coated with hydroxyapatite by plasma spray to be used as biodegradable implant material and their in-vitro corrosion behaviors are to be examined. There are a number of researches on the production of biodegradable cortical screws and plates used in orthopedic surgery in last decade. The advantage of biodegradable implants is that they do not need to be surgically removed. Moreover, the elastic modulus and the mechanical properties of magnesium are relatively close to those of the human bone, and this prevents the phenomenon of the human bone named "stress shielding. During this study, the hydroxyapatite coating processes, characterizations and corrosion behaviors of AZ31 and AZ91 will be examined. The aim of this work is to determine the optimal coating conditions for magnesium alloys for biodegradable implants. As a result of the plasma spray coating, the corrosion rate has decreased from about 1.2 mm/year to 0.4 mm/year.