Quantities of flavins and activities of D-amino acid oxidase in the liver and kidney of vitamin D injected rats (100,000 I.U. or 150,000 I.U.) were estimated. The quantities of total flavins and FAD in the liver and kidney of hypervitaminotic rats were considerably lower than those of normal rats. D-Amino acid oxidase activities of hypervitaminotic rats were slightly lower than those of normal rats.