Two coherent bistatic radio systems were used to observe auroral radio reflections under geometrical conditions which would favor the detection of ion-acoustic waves in the auroral ionization. The displaced "line" spectrum, characteristic of scattering by ion-acoustic waves, was a prominent feature of some of the observations but the strength of the wave-scattered component varied widely relative to the non-wave-scattered components. It is concluded that ion-acoustic waves do indeed occur in the auroral plasma but that such waves cannot be the only source of radio-wave scattering in aurora.