An implantable hermetically sealed living tissue stimulator which includes a coil in which current is induced by an external alternating magnetic field is disclosed. All the stimulator circuit components except for one or more electrode leads are hermetically sealed within a hermetic container formed of a biocompatible metal of a thickness T, and having an electrical resistivity .rho., where T/.rho. .ltoreq. 0.03, T being in mils and .rho. in microhm-cm. The metal thickness T is not more than 5 mils and preferably not more than 3 mils, and the electrical resistivity .rho. is not less than 75 microhm-cm and preferably not less than 100 microhm-cm, in order to reduce the portion of power induced in the stimulator by the magnetic field which is dissipated as heat in the hermetic metal container and to increase the portion of the induced power which penetrates the container and induces the current in the coil.