A clinical microwave device was used to heat the head and ear of the North American bullfrog in order to observe the temperature dependence of tuning in the sacculus, an organ known to possess the capability of electrical resonance in its hair cells. In tuning curves derived from reverse correlation analysis with noise stimuli, the temperature dependencies of the frequencies of tuning peaks and notches typically exhibited Q 1 0 s less than 1.1; whereas the frequencies of electrical resonances are expected to have Q 1 0 s of the order of 1.7. Therefore we conclude that electrical resonances are not significantly involved in tuning in the bullfrog sacculus.