Oral administration of kaolin (50-200 gm.) was effective in controlling parathyroid tetany and in preserving the life of completely thyroparathyroidectomized dogs. The effect of kaolin is perhaps due to absorption of toxic products of bacterial growth in the gastrointestinal tract and the predominance of an aciduric intestinal flora which it brings about. These experiments are interpreted to support the view that parathyroid tetany is an intoxication and that the responsible toxic substances in non-pregnant animals arise chiefly in the gastro-intestinal tract as a result of bacterial proteolysis.