Abstract— The concentration dependence of the magnetic properties of iron–germanium alloys before and after thermomagnetic treatment, which represents an annealing of alloy samples in the ferromagnetic state in a permanent or alternating magnetic field (magnetic field annealing – MFA), has been investigated. It is shown that before MFA, with an increase in the germanium content in the range of 3–30 at % Ge, the coercive force increases and the residual induction decreases. As a result of thermomagnetic treatment, in the alloy samples magnetic anisotropy is induced: the magnetic hysteresis loops become narrower, the residual induction increases, and the coercive force decreases. Thermomagnetic treatment is effective for Fe–Ge alloys with a germanium content from 6 to 18 at %, and its highest efficiency is observed at 12 at % Ge. Features of the structural state of iron–germanium alloys and their role in the formation of magnetic properties during annealing in a magnetic field are discussed.