Repeated intravenous injections of ferric chloride are followed by an increase in the survival time of tuberculous rabbits. In the particular series of experiments reported this increase amounts to about 78 per cent over the average survival time of control rabbits. Tuberculous animals repeatedly injected with ferric chloride increase in weight during part of the period of these injections. The level reached in the series studied markedly exceeds that attained by control rabbits. Both control and experimental animals die of generalized tuberculosis. There is no indication at the time of death of any differences in the degree of pathological involvement between the two groups of animals.