A new extractive paper-chromatography for the colorimetric determination of micro amounts of uranium with arsenazo III in rocks has been studied. The sample solution in nitric acid meduim was developed on the filter paper with butanone-MIBK-HNO3 H20 (80:80:20:20) for 1-2 hrs. The Rf values were found to be 0.9-1.0 and 0.4-0.5 for U and Th respectively, the other elements such as RE, Fe, Ti, Mn, W, Ni, Co and Mg were zero.. This method could be applied to the determination of 0.0000x-0. OOx% uranium in rocks.