It has long been postulated that vibrothermographic heating—the heating of cracks due to sound or vibration‐induced rubbing—may be frequency dependent. It has been difficult to factor out the innate frequency dependence of the heat‐generation process from the geometry‐dependent mode structure. We present experiments showing the heating of cracks in slender Inconel∕Titanium specimens at transverse resonance. Different resonant modes vibrate at different frequencies but load the crack in the same way (Mode I). The results show a clear increase of heating with vibration frequency.