A large dose of 2, 8‐dioxyadenine‐14C was injected intravenously into rats and its fate followed at several intervals during the first 24 hours after administration. The distribution of the radioactive material throughout the various tissues or organs was calculated and expressed as a percentage of the injected dose as well as a specific activity per unit organ weight. It appears that dioxy‐adenine is rapidly distributed throughout the organs and tissues of the rats and that specific concentration occurs in a few organs. High retention of the radioactive material and a very high specific activity are observed in the kidney. Smaller but significant concentrations of the14C‐compound are also observed in muscle and skin, and cannot be attributed to the presence of residual blood. The radioactive material is gradually released from these tissues and, by 24 hours after injection, 92 per cent of the injected dose is found in the urine. Microscopic observation shows deposition of crystals in the kidney. Crystals are also present in the urine and appear as small slightly yellow