A possible advantage of binaural hearing aids was investigated by determining whether words heard binaurally were more intelligible than words of equal power heard monaurally. Six normal listeners wereSs, and their monaural ear (whether left or right) was chosen so that its sensitivity, when averaged for all listeners, was approximately equal to that of the other ear. EachSlistened to ten lists of fifty words; half of the lists were presented monaurally and half binaurally. Five different intensity levels were used, covering a range of 20 db. At every level, the binaural condition, in which each ear received the same power as the monaural ear at the same level, proved superior to the monaural condition. But if one allowed for the fact that when listening with two ears the total power was twice as great as for one ear, this superiority disappeared. The sum of the powers in each ear was no more effective than the same power in one ear. Hence no evidence was found that binaural hearing aids would improve intelligibility.