An implant consisting entirely or in part of a biocorrodible magnesium alloy having the compositionGd:2.7-15.0 wt%,Zn:0-0.5 wt%,Zr:0.2-1.0 wt%,Nd:0-4.5 wt%,Y:0-2.0 wt%,where magnesium and impurities due to the production process account for the remainder to a total of 100 wt%.