The pitch of a tone sounding in one ear can be changed by introducing a tone of the same frequency in the other ear, provided both tones are of fairly high intensity. The change in pitch, obtained in the present expt. with tones of a 95 decibel loudness level, is in the same direction as that which results from an increase in the physical intensity of the tone; that is, the pitch shifts downward for low frequencies, upwards for high frequencies, and to a negligible extent for a frequency region between. (1000-3000 cycles). Furthermore, the pitch of a tone can be changed by introducing a tone of different frequency in the other ear, provided, again, that both tones are of fairly high intensity. The direction of the change, obtained in the present expt. with tones of a 95 decibel loudness level, is almost without exception the same as that found to occur when a tone of the same frequency is presented in the other ear. The pitch of a tone is thus shown to be a function of binaural interaction; control expts. show that this interaction is not peripheral in nature. The results of the present expt. do not support the hypothesis of the mediation of the perception of pitch by the position of maximal stimulation.