A biodegradable implant is formed of a magnesium alloy having 3 to 7% by weight Zn, 0.001 to 0.5% by weight Ca, the remainder being magnesium containing total impurities, which promote electrochemical potential differences and/or the formation of intermetallic phases, in a total amount of no more than 0.0048% by weight, wherein the total impurity contains elements selected from a first group of Fe, Si, Mn, Co, Ni, Cu, Al, Zr and P and elements selected from a second group of rare earths having the ordinal numbers 21, 39, 57 to 71 and 89 to 103.
