In order to practically exploit the large magnetostriction effects observed in Fe-based alloys, the magnetoelastic interactions in these materials have to be understood. Until now, Fe–Ga alloys have exhibited the largest magnetostriction in non-rare-earth alloys, but they also present a complex phase diagram, which does not allow a simple interpretation of magnetoelastic coupling at large Ga concentrations (above 20%). Fe–Ge alloys, which show an increase in the tetragonal magnetostriction but not as pronounced as in Fe–Ga, bring, however, a cleaner and more reproducible crystalline structure for the entire range of practical compositions. Measurements of elastic constants using resonant ultrasound spectroscopy in a saturating magnetic field and as a function of temperature for different compositions of the Fe–Ge alloys will be presented and contrasted to previously published Fe–Ga results. The addition of Ge to the structure of alpha-Fe softens the c′=(c11−c12)/2 shear modulus significantly. For example, only with 7 at. % Ge addition, c′ falls by 21% from the 48 GPa value of the pure Fe crystal.