Abstract: The analysis of rose bengal-131I preparation, by PC has been investigated. Analytic conditions were determined. Chromatographic separation was carried out by the ascending technique with solvent system: n-amyl alcohol-cone, ammonium hydroxide-water (0.5:2:100) on'domestic "Xin Hua" medium speed chromatographic paper, Whatman (?) 1 or (?) 2 paper. The front was 25cm. The time was 2 to 4 hours. The method is suitable for routine quality control of the preparation. After one-dimensional chroma-tography, content of 131I- and tetraiodotetrachloro-fluorescein in the preparation can be determined at the same time.Deiodination of sample on paper has also been studied. Before chromatographic separation, the sample point should not be dried by infrared lamp, otherwise deiodi-nation will occur, and the content of iodide ion will be increased.