Noise-induced hearing loss appears to result from energy depletion in the hair cells. Cell membrane permeability is increased in hypomagnesemia, causing Na+ and Ca++ influx, with subsequent increase in energy-dependent ion-pumping. Energy exhaustion is further enhanced by hypomagnesemia-induced vasoconstriction. Dietary supplementation with magnesium was shown to lessen hearing loss in noise-exposed rats. It is postulated that the same mechanisms may act in man and the possible benefit of magnesium supplementation for noise-exposed workers should be investigated.