A review is presented of recent results of ultrasonic investigations of rare earth–iron compounds and alloys. The discussion is divided into three sections. The first describes results of sound velocity measurements of single crystal Tb0.3Dy0.7Fe2 as a function of magnetic field strength and orientation with respect to the crystallographic axes. In the second part recent work on polycrystalline and amorphous samples, including evidence for simultaneous propagation of two different types of magnetoelastic waves is presented. A model developed to describe this phenomenon is outlined as well. Finally a transmission experiment in a single crystal (Tb0.3Dy0.7Fe2) is described. Resonant-like transmission is shown to take place when an applied magnetic field is so oriented as to produce almost equal velocities for C44 and C11-C12 modes.