The antigen quantities in blood and urine of rabbits, intravenously injected with crystalline hen's egg albumin and egg white, were measured by immunological methods. The natures of urinary excreted antigens were studied by filter-paper electrophoretic method. The results were as follows: 1) Intravenously injeeted crystalline hen's egg albumin disappeared from the circuration in 7 days after injection. 2) Urinary excreted antigen almost disappeared in 9 days after injection. 3) Antibody formation began on the 3rd day and reached to the maximum in 6~7 days after the injection of antigen. 4) The filter-paper electrophoretic pattern of urinary excreted antigens, at 1 hour after injection, showed one component. This component moved on the electrophoretic filter paper the same rate as A(l)-peak of original crystalline hen's egg albumin. The pattern of urinary excreted antigen at 24 hours after injection, showed two components, the fast and the slow moving ones. the antigenicities of extracts of these two components were measured by the immune reaction against anti-crystalline hen's egg albumin rabbit sera, to determine the quality of these components. The rate of antigenicity of the fast moving component to the slow moving one was 3.2: 1. From these results, it was inferred that the fast moving component was egg albumin, while the slow moving one was denatured egg albumin. 5) The filter-paper electrophoretic pattern of urinary excreted antigens at 24 hours after injection of egg white, showed almost one component. And the antigenicity of the extract of this component was measured by the immune reaction against anti-crystalline hen's egg albumin rabbit sera. From above experiments, it was demonstrated that only egg albumin was excreted inurine, while the other components of egg white were not excreted in urine.