Rice plants were supplied after heading with radioactive P." as Na2HPO4. After 24, 72. and 192 hours, plants were harvested, and separated into several parts. Then they were analyzed for their P content. At the same time, their phosphorous compounds were fractionated and measured the radioactivity. The concentration of P." was highest in the boot leaf, which was the newest, and that coincided with Bidduiph's results. P" in the leaf, then, gradually translocated into the ear and accumulated. Total P as phosphatide and nuclein decreased in the leaf and stem during this period, but P" as these forms increased in every parts of plants. That shows vigorous renewal of phosphatide and nuclein at that period in these organs.