NO ATTEMPT will be made to describe this fraction of the B complex from the standpoint of pharmacology. It has been used empirically and with considerable success in a number of conditions, apparently unrelated pathologically, such as granulocytopenia, vomiting of pregnancy, and radiation sickness, and, with reported improvement, in paralysis agitans, or the Parkinson syndrome, and other organic diseases of the nervous system. A year ago one of us observed a patient with inner ear deafness, that is, with shortened bone conduction and loss of hearing principally for high tones, whose audiograms taken over a period of years showed progressive deafness and who complained that he heard a peculiar snapping noise in one ear. The symptoms were not relieved by local treatment or by the administration of nicotinic acid (niacin) or neostigmine, but after five weeks of treatment with pyridoxine a 10 to 15 decibel improvement was noted in hearing